bp2build: build static version of libstdc++.

This CL adds the ability to filter cc_library modules to only generate
their static variant of their shared variant isn't ready.

For example, the libstdc++ library is buildable as a static library,
which libc depends on. However, the shared variant of libstdc++ depends
on libc, which has to come later.

This CL introduces that abstraction to break up bp2build conversion into
more atomic steps to help with conversion.

Test: TH (bazel build //bionic/... incl. libstdc++'s static variant)
Bug: 186489250
Bug: 186822597

Change-Id: I3e2fe748e4e3d3b656760da4807f342d67c8f45f