Convert all the test legs to Helix

[mikem8361]

Instead of running tests on the host machine, send them to helix. This will allow testing on more platforms like FreeBSD or Alpine too.

[mikem8361]

Also, don’t publish packages unless all the test legs pass

[hoyosjs]

For this, also we need to move the copying of source for CLI built tests (like singlefile) to a build phase artifact, such that deployment can be xcopy deployed.