[6.4.x] Enable Android emulator testing with the 6.4 snapshot toolchain employing swift-build in SwiftPM

[finagolfin]

• Explanation: Add Android testing and update CI workflow version

• Scope: Only minor CI changes

• Issues: None

• Original PRs: Cut down and updated version of Enable Android emulator testing with the snapshot toolchains employing swift-build in SwiftPM #1745

• Risk: None from code, as no changes there; very low from these CI changes, as all the same workflows are passing

• Testing: Passing on trunk for the last month and a half

• Reviewers: @grynspan

[finagolfin]

@grynspan, these nightly-main workflows fail on all 6.4 pulls, can remove those non-Android ones too if you'd like.

[finagolfin]

@stmontgomery, anything holding up getting this in? The three failing nightly-main workflows on this pull are failing on all 6.4 pulls, eg this last one, so I can just remove those as part of this pull, if wanted.

This will give better test coverage for the 6.4 branch.

[finagolfin]

Rebased on latest 6.4 branch

[finagolfin]

Simply rebased again, @harlanhaskins, could you take a look?

[finagolfin]

Rebased and updated workflows to latest tag.

@jerryjrchen, could you review? The others I pinged don't seem to be too active here lately, may be busy with other stuff.

[stmontgomery]

@finagolfin I'm OK with taking this, but since this is targeting the release/6.4.x branch can you fill out the PR template?

Also note that 6.4.1 just recently branched, so consider whether you want to include this change in the release/6.4.1 branch as well, and post a separate PR for that if so. I think it's too late to consider this for the release/6.4.0 branch.

[finagolfin]

since this is targeting the release/6.4.x branch can you fill out the PR template?

Sure, I thought it's not needed since these are only minor CI changes, not code changes, but can add that info here if you prefer.

consider whether you want to include this change in the release/6.4.1 branch as well, and post a separate PR for that if so.

Saw that, will do.

I think it's too late to consider this for the release/6.4.0 branch.

Don't much care, as this is a pure CI pull, which only adds a bit more testing and keeps the swiftlang workflows up to date.

That just depends on your CI policy: some want the latest workflows for all tested branches on their repos, others may not.

Given that almost everything is passing on this latest CI run- with the one linux failure using the Swift 6.5 toolchain failing on other 6.4 pulls also, ie unrelated to this CI pull- I think it is better to use the latest swiftlang workflows for 6.4.0 too, but up to you.

[grynspan]

A 6.4.1 cherry-pick is probably not necessary as changes are going to be minimal for that release.

[finagolfin]

Rebased and added the release branch info asked for.

[stmontgomery]

Thanks @finagolfin!