new_variant: add end-to-end test

Add an end-to-end test for to verify that creating
firmware for a new variant still works.

TEST=See testdata/ for full details. Short version:
`cd testdata` then pick a reference board to test:
`./ hatch`
`./ puff`
`./ volteer`
`./ trembyle`
`./ dalboz`
`./ waddledee`
`./ waddledoo`
Watch the output to see the build succeed and then clean up all of
the generated CLs. Run `repo status` to see that there aren't any
modified files hanging around.

Change-Id: I33157f41f398c0dc60a453584de71b538dd9d37c
Tested-by: Paul Fagerburg <>
Reviewed-by: Rob Barnes <>
Reviewed-by: Greg Edelston <>
Commit-Queue: Paul Fagerburg <>
3 files changed