Remove spurois change that bungles CR

This went up in a separate CR anyway.
dding DxCompile integration tests

This strategy could probably be used for AaptGen as well,
somewhere down the line.
DxCompile integration test up and running

Not quite done, testing for the artifact has a bug.
But close.
Mostly working integration test

Currently resolving the mass of not-quite-constants into a
classmethod.
Integration test for dx_compile way less embarassing

ALmost done, lets see if we can verify the artifact.
I need to find where they are sending the output to.
Finished DxCompile- style, remove unused modules from BUILD

I am considering moving the output of DxCompile (the classes.dex)
into the 'dist' folder, for packaging purposes. If that happens
then I want to remember to add an artifact check at the end
of this integration test. TODO added.
Repond to CR

Capitalize constant (dumb mistake); add error catch if
target.walk returns no classes.
Hook DxCompile into the invaliadtion machinery

This appears to work , although I confess I haevn't plumbed
exactly what this is doing under the hood yet. I am sure
some hidden issue will require that soon enough.
Move dx_integration test as just an integration test

This way it won't get run for every CI, only when the
tester asks specifically for integration tests.