Move Launcher classes shared between tests and prod in a separate lib

This is necessary because otherwise those are included in several gradle projects. Gradle doesn't support the same files imported in different projects, and it removes them from a random one if it happens, resulting in missing symbols.

This extracts the shared files in a new target, and adds it as dep of the original target.

Test: Build launcher + execute a few tests manually with gradle + verify that Launcher.java can resolve all symbols with gradle config
Bug: 262267728
Change-Id: Ida5b25c45320d517603834112f4699e4d3344c03