This PR makes the Server agent(*) attempt to make a connection with a
Client before marking it as NodeStatusDown due to a missed heartbeat.

Manually double-checking responsiveness of the Client before marking
it down paves over issues where the Client may still be fine, but
coordination between Client, the server it is reporting status to,
and the leader managing heartbeat timers is not lined up.

(*) Who _should_ be the leader, but might not be in the immediate
aftermath of something triggering an election.

Potentially resolved causes of erroneous down-ed nodes:

1. Stale leader w/ expiring timers marking nodes it should not
2. Overloaded leader not responding to incoming update RPCs before timers expire

These options are mutually exclusive but, since `-hcl2-strict` defaults
to `true` users had to explicitily set it to `false` when using `-hcl1`.

Also return `255` when job plan fails validation as this is the expected 
code in this situation.

Nomad is generally compliant with the CSI specification for Container
Orchestrators (CO), except for unimplemented features. However, some storage
vendors have built CSI plugins that are not compliant with the specification or
which expect that they're only deployed on Kubernetes. Nomad cannot vouch for
the compatibility of any particular plugin, so clarify this in the docs.
Co-authored-by: Derek Strickland <1111455+DerekStrickland@users.noreply.github.com>

Log lines which include an error should use the full term "error"
as the context key. This provides consistency across the codebase
and avoids a Go style which operators might not be aware of.

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: James Rasell <jrasell@hashicorp.com>

In order to add an E2E test to cover token expiration, the server
config has been updated to include a low minimum allowed TTL
value. For ease of reading, the max value is also set.

It is really unclear on how to use this feature. it took me a while to find this, so I thought I would purpose how to use this.

* Merge release 1.3.5 files

* Generate files for 1.3.5 release

* Prepare for next release
Co-authored-by: hc-github-team-nomad-core <github-team-nomad-core@hashicorp.com>

The ACL command docs are now found within a sub-dir like the
operator command docs. Updates to the ACL token commands to
accommodate token expiry have also been added.

The ACL API docs are now found within a sub-dir like the operator
API docs. The ACL docs now include the ACL roles endpoint as well
as updated ACL token endpoints for token expiration.

The configuration section is also updated to accommodate the new
ACL and server parameters for the new ACL features.

This adds a new ACL test suite to the e2e framework which includes
an initial test for ACL roles. The ACL test includes a helper to
track and clean created Nomad resources which keeps the test
cluster clean no matter if the test fails early or not.

PR #12130 refactored the test to use the `wantPeers` helper, but this
function only returns the number of voting peers, which in this test
should be equal to 2.

I think the tests were passing back them because of a bug in Raft
(https://github.com/hashicorp/raft/pull/483) where a non-voting server
was able to transition to candidate state.

One possible evidence of this is that a successful test run would have
the following log line:

```
raft@v1.3.5/raft.go:1058: nomad.raft: updating configuration: command=AddVoter server-id=127.0.0.1:9101 server-addr=127.0.0.1:9101 servers="[{Suffrage:Voter ID:127.0.0.1:9107 Address:127.0.0.1:9107} {Suffrage:Voter ID:127.0.0.1:9105 Address:127.0.0.1:9105} {Suffrage:Voter ID:127.0.0.1:9103 Address:127.0.0.1:9103} {Suffrage:Voter ID:127.0.0.1:9101 Address:127.0.0.1:9101}]"
```

This commit reverts the test logic to check for peer count, regardless
of voting status.

* Update Consul Template dep to support Nomad vars

* Remove `Peering` config for Consul Testservers
Upgrading to the 1.14 Consul SDK introduces and additional default
configuration—`Peering`—that is not compatible with versions of Consul
before v1.13.0. because Nomad tests against Consul v1.11.1, this
configuration has to be nil'ed out before passing it to the Consul
binary.

Neither the `os.Setenv` nor `t.Setenv` helper are safe to use in parallel tests
because environment variables are process-global. The stdlib panics if you try
to do this. Remove the `ci.Parallel()` call from all tests where we're setting
environment variables.

Update the on-disk format for the root key so that it's wrapped with a unique
per-key/per-server key encryption key. This is a bit of security theatre for the
current implementation, but it uses `go-kms-wrapping` as the interface for
wrapping the key. This provides a shim for future support of external KMS such
as cloud provider APIs or Vault transit encryption.

* Removes the JSON serialization extension we had on the `RootKey` struct; this
  struct is now only used for key replication and not for disk serialization, so
  we don't need this helper.

* Creates a helper for generating cryptographically random slices of bytes that
  properly accounts for short reads from the source.

* No observable functional changes outside of the on-disk format, so there are
  no test updates.

cgroups: refactor v2 kill path to use cgroups.kill interface file

cleanup: tidy up helper package some more

"path" parameter doesn't work, should be command

acl: add token expiration and ACL role functionality

[ui] Variables Rename

This PR refactors the cgroups v2 group kill code path to use the
cgroups.kill interface file for destroying the cgroup. Previously
we copied the freeze + sigkill + unfreeze pattern from the v1 code,
but v2 provides a more efficient and more race-free way to handle
this.

Closes #14371

This reverts commit b9fec224.

cleanup: more cleanup of slices that are really sets

Variables rename

Fixes #14367

Nomad reconciles services it expects to be registered in Consul with
what is actually registered in the local Consul agent. This is necessary
to prevent leaking service registrations if Nomad crashes at certain
points (or if there are bugs).

When Consul has namespaces enabled, we must iterate over each available
namespace to be sure no services were leaked into non-default
namespaces.

Since this reconciliation happens often, there's no need to require
results from the Consul leader server. In large clusters this creates
far more load than the "freshness" of the response is worth.

Therefore this patch switches the request to AllowStale=true