Add missing repo boundary files

[fmeum]

[fmeum]

@Wyverald Could you review this as well?

[fmeum]

@vladmos I fixed one test failure in the buildifier integration test, but I don't understand the test setup for the remaining another_test_dir failure to the extent required to fix the new failure caused by that fix.

Edit: I pushed a slightly hacky fix.

[fmeum]

The Windows failure seems unrelated.

[fmeum]

I fixed the CI failures.

[Wyverald]

i'll go ahead and merge this since it looks fairly straightforward.