deps: upgrade go-plugin dependency

This PR brings go-plugin up to date from ~v1.0.1 to v1.4.0 (about 18 months)
with a grab-bag of bux fixes.

api: set operator query meta

Set the query meta for LicenseGet request. It's expected by api consumers to determine the raft index.

Also, remove protobuf installation: it's not used anymore.

"Bottles" have been migrated to GitHub packages, so we need to update homebrew
to point to that new source before installing the `protobuf` formula.

The error messages are reversed from tests performed above them.  The test uses the `validateJobUpdate()` function, but ignores the text of the error message itself.

docs: clarify alloc signal behavior

The API docs don't make it immediately clear that the alloc signal API signals *all* tasks in an allocation if the `Task` parameter is omitted. You have to dig all the way down into the alloc runner to discover that behavior: https://github.com/hashicorp/nomad/blob/v1.0.4/client/allocrunner/alloc_runner.go#L1189-L1213

* go get on the remote mac instance installs with read-only, allow for rm step

* Update scripts/release/mac-remote-build
Co-authored-by: Mahmood Ali <mahmood@hashicorp.com>
Co-authored-by: Mahmood Ali <mahmood@hashicorp.com>

Plugins could potentially ignore the `max_entries` field and return a list of
entries that is greater, so we slice the return value in the server RPC to
enforce these value. But page sizes less than the number of entries for the
external CSI ListVolumes and ListSnapshots RPCs could cause a panic, so fix
the boundary checking.

CNI: add fallback logic if no ip address references sandboxed interface

A demo for the CSI hostpath plugin, used primarily for development
purposes. This reproduction has been used for testing during our CSI
implementation work, and this changeset makes that public.

The archive does not include the `pkg/windows_amd64` path and unpacking the
archive happens in the installation directory.

There was a small typo of "namespacecs" instead of "namespaces"

The E2E provisioning used local-exec to call ssh in a for loop in a hacky
workaround https://github.com/hashicorp/terraform/issues/25634, which
prevented remote-exec from working on Windows. Move to a newer version of
Terraform that fixes the remote-exec bug to make provisioning more reliable
and observable.

Note that Windows remote-exec needs to include the `powershell` call itself,
unlike Unix-alike remote-exec.

The AWS EBS CSI plugin was observed to return a EOF when we get to the end of
the paging for `ListSnapshots`, counter to specification. Handle this case
gracefully, including for `ListVolumes` (which EBS doesn't support but has
similar semantics).

Also fixes a timestamp formatting bug on `ListSnapshots`

Split the EBS and EFS tests out into their own test cases:
* EBS exercises the Controller RPCs, including the create/snapshot workflow.
* EFS exercises only the Node RPCs, and assumes we have an existing volume
that gets registered, rather than created.

The goal is to always find an interface with an address, preferring
sandbox interfaces, but falling back to the first address found.

A test was added against a known CNI plugin output that was not handled
correctly before.

Fix HCL2 panics when parsing undefined variables

* website: add customer testimonial to homepage

* website: remove one testimonial, remove product logos

makefile cleanup

With the updated undefined variable code, we attempt to pick the text of
`${....}` verbatim from the hcl body. Previously, we'd attempt to
regenerate the string from the AST and pray it matches input; the
generation is lossy, as the same AST can represent multiple variations
(e.g. `${v.0}` and `${v[0]}` have the same HCLv2 AST). In this change,
we attempt to go back to the hcl2 source and find the string snippet
corresponding to the variable reference.

Update hcl/v2 to point to https://github.com/hashicorp/hcl/commits/nomad-v2.9.1+tweaks1

Updates stackmenu to latest

Our API client `delete` method doesn't include a request body, but accepts an
interface for the response. We were accidentally putting the request body into
the response, which doesn't get picked up in unit tests because we're not
reading the (always empty) response body anyways.