Unify most of our CI under github actions

[Mpdreamz]

Unifies our CI under one organization.

• Move integration builds to github actions

  • Utilizes caching so we builds can benefit from already downloaded Elasticsearch and zips.
  • Easier test matrix.
  • Tests are only reported if they fail

• Move canary build away from AppVeyor (and Azure devops)

  • Now publishes prereleases on builds on integration branches
  • Move to common .NET feed on feedz.io

• Stale docs and unit tests are now their own seperate jobs.

  • Unit test always report the status back using this annotator

• Only test one random overload instead of all 4.

Moves the general build to utilize nuget lock files, this increases restore times locally and on CI.
- We now also cache nuget packages on ci based on the hash of all lock files.

[stevejgordon]

LGTM! Great stuff!

Once merged and backported, I can rebase a few of the 7.12 feature PRs onto this to give it some real changes to test?

[Mpdreamz]

@stevejgordon backported to 7.12 will work on a manual backport to master now :)