Add a check to verify the base commit build status in the release process

[ironage]

As discussed in the round table today, we'd like the automated process to check that the base branch is in a releasable state. This gives us confidence in the release, and allows us to skip evergreen checks on "changelog/version" only changes in the release process.

These script changes use the Github API to check the status of the commit being released. It writes the status in the "prepare" PR description along with a link to the build page. This is a non-blocking way of quickly seeing the state of the build without requiring that it pass to release. This allows us to manually inspect the build and make a release even if there are failing checks that have been deemed "sporadic failures" by the releaser.

[coveralls-official]

Pull Request Test Coverage Report for Build james.stone_556

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 54 unchanged lines in 9 files lost coverage.
• Overall coverage decreased (-0.004%) to 90.838%

---

Files with Coverage Reduction	New Missed Lines	%
src/realm/index_string.cpp	1	85.17%
src/realm/util/serializer.cpp	1	90.43%
test/test_query2.cpp	1	98.73%
src/realm/query_expression.hpp	2	93.81%
src/realm/sync/network/network.hpp	7	85.28%
src/realm/util/file.cpp	7	78.2%
test/sync_fixtures.hpp	7	75.56%
src/realm/sync/noinst/client_impl_base.cpp	10	82.72%
src/realm/sync/noinst/server/server.cpp	18	73.34%

Totals
Change from base Build 2379:	-0.004%
Covered Lines:	214588
Relevant Lines:	236231

---

💛 - Coveralls

[michael-wb]

LGTM - just one small request

[michael-wb]

So this just gives a ✅ or ❌ if the sum total of the checks failed or not?
Maybe for reference, make the $GIT_HASH value a link to the PR/commit used to to provide this status.

[ironage]

Yes, I am taking advantage that the text is rendered in the Github PR description, which expands the text of the ✅ or ❌ to render the emoji. In the same way, Git hashes in a Github PR automatically become links to the commit, from that it should be easy to poke around and find the failing check.