bp2build conversion for rscript srcs in cc modules

Bazel does not support using .rscrip/.fs files as cc srcs.
For a module foo with foo srcs, Bp2build will create a bazel
target of rule class rscript_to_cpp with name foo_renderscript
which will have only the renderscript files as srcs.
Bp2build will also create a target foo with the expected cc rule class.
The foo target will have all other src files as srcs and will also
have the target foo_renderscript as another src.

Bug: 210509914
Test: bp2build testing & b build target rstest-latency
Change-Id: Ifdc55051a3595f5fcf54eab8b59e11e9351e141c