Ensure that api test agent is terminated gracefully. This is desired for
two purposes:
First, to ensure that the logs are fully flished out. If the agent is
killed mid log line and go test doesn't emit a new line before `---
PASS:` indicator, the test may be marked as failed, even if it passed.
Sample failure is https://circleci.com/gh/hashicorp/nomad/72360 .
Second, ensure that the agent terminates any auxiliary processes (e.g.
logmon, tasks).
* Divest api/ package of deps elsewhere in the nomad repo.
This will allow making api/ a module without then pulling in the
external repo, leading to a package name conflict.
This required some migration of tests to an apitests/ folder (can be
moved anywhere as it has no deps on it). It also required some
duplication of code, notably some test helpers from api/ -> apitests/
and part (but not all) of testutil/ -> api/testutil/.
Once there's more separation and an e.g. sdk/ folder those can be
removed in favor of a dep on the sdk/ folder, provided the sdk/ folder
doesn't depend on api/ or /.
* Also remove consul dep from api/ package
* Fix stupid linters
* Some restructuring
