Add android.test.legacy target

Adds a library that builds against the public API and so can be safely
statically included into applications to avoid them having to depend
on the android.test.base and android.test.runner runtime libraries.

Bug: 30188076
Test: make checkbuild
Change-Id: Iae7e3c64392e11035322092ed8e194740ba2d321
2 files changed