Added new external driver for Pot to nomad documentation

Without a `LocalServicePort`, Connect services will try to use the
mapped port even when delivering traffic locally. A user can override
this behavior by pinning the port value in the `service` stanza but
this prevents us from using the Consul service name to reach the
service.

This commits configures the Consul proxy with its `LocalServicePort`
and `LocalServiceAddress` fields.

Fix two broken links in the Documentation & Guides section, namely Advanced Job Scheduling on Nomad with Affinities and Increasing Nomad Fault Tolerance with Spread

I thought #6343 would fix the flapping but it didn’t 😞

fixed incorrect CLI `-help` in `job deployments`

listed `-all-allocs` instead of `-all`

This fixes a race condition in the pseudo-relationship between a
TaskState and a Task that was causing the Consul Connect proxy tag
to sometimes show on the wrong task. There’s no direct Ember Data-style
relationship between a TaskState and its Task; instead, it’s determined
by searching for a Task with the matching name. The related Task was
sometimes stored before everything was ready and not recalculated when
the name became known. This ensures the relationship is accurate if the
TaskState’s name property changes.

docker: remove containers on creation failures

Corrected minor typo ("Eslevier" --> "Elsevier")

Add Host Volumes E2E test

Add a test helper that restarts a specific client node running under
systemd using a `raw_exec` job.

The docker creation API calls may fail with http errors (e.g. timeout)
even if container was successfully created.

Here, we force remove container if we got unexpected failure.  We
already do this in some error handlers, and this commit updates all
paths.

I stopped short from a more aggressive refactoring, as the code is ripe
for refactoring and would rather do that in another PR.

Fix bugs around docker start retries

* reduce memory required for logmon, docker_logger and executor processes

* comment early importing

cli: emit job version number proper

Update GNUmakefile

Cert auth generation echo fixed

client: Fail startup if host volumes do not exist

Tweaks for UI README

ui: protect against no services

UI: Restore local headless testing

Protect against case where an alloc has no services and avoid
dereferencing null.

Here, we ensure that the model and test serializers mimic the API by
having nil TaskGroup.Services instead of an empty array.

Hoist Volume.Config.Source into Volume.Source

Co-Authored-By: Michael Schurter <mschurter@hashicorp.com>