This PR fixes an issue where template restarts would count twice since
it was emitting a restarting event.

drivers: pass logger through driver plugin client

drivers/docker: handle shutdown of upgraded tasks correctly

website: redirect to new scheduling doc

server/vault: tweak error messages

* initial structure

* add to affinity guide

* add to affinity guide

* update affinity guide

* spread guide

* update content

* update step 3 to spread stanza

* update

* add wording to motivate the use of spread and affinity

* improve guide description and use clearer wording to distinguish constrain from affinity

* clarify challenge to user with specific example

* improve wording in the solution section

* incorporate rest of suggestions into affinity guide

* modify spread guide description

* improve wording of spread docs

* change instance count from 5 to 10 to more easily show spread

* improving spread guide and changing demo architecture

* motivate spread a bit more

* clarification about spread

* fix wording

Closes #5139

This fixes a panic whenever driver plugin attempts to log a message.

docker: only log missing bridge_ip on initial fingerprint

plugins/drivers: change stats interval to duration type in proto

Documentation for preemption

Documentation fixes for affinity and spread

Co-Authored-By: preetapan <preetha@hashicorp.com>

Add Datacenters to the JobListStub struct

e2e tests for upgrade path to driver plugins

* master: (23 commits)
  tests: avoid assertion in goroutine
  spell check
  ci: run checkscripts
  tests: deflake TestRktDriver_StartWaitRecoverWaitStop
  drivers/rkt: Remove unused github.com/rkt/rkt
  drivers/rkt: allow development on non-linux
  cli: Hide `nomad docker_logger` from help output
  api: test api and structs are in sync
  goimports until make check is happy
  nil check node resources to prevent panic
  tr: use context in as select statement
  move pluginutils -> helper/pluginutils
  vet
  goimports
  gofmt
  Split hclspec
  move hclutils
  Driver tests do not use hcl2/hcl, hclspec, or hclutils
  move reattach config
  loader and singleton
  ...

Document devices

Co-Authored-By: dadgar <alex@hashicorp.com>

Merge branch 'f-driver-upgradepath-test' of https://github.com/hashicorp/nomad into f-driver-upgradepath-test

* 'f-driver-upgradepath-test' of https://github.com/hashicorp/nomad:

drivers: add docker upgrade path and e2e test

Merge branch 'f-driver-upgradepath-test' of https://github.com/hashicorp/nomad into f-driver-upgradepath-test

* 'f-driver-upgradepath-test' of https://github.com/hashicorp/nomad:
  Apply suggestions from code review

Also reorganize the docs so that scheduling has subpages in it

ci: run seperate build jobs for slower packages