Passing variables via a makefile instead of
rblf_cli / rblf_env allows us to give them correct
types while converting the makefile to starlark,
as opposed to the variables always being strings
when given via rblf_cli / rblf_env.
This also allows us to remove some hand-converted
starlark code.
Bug: 201700692
Test: ./out/soong/rbcrun ./build/make/tests/run.rbc
Change-Id: I58c4f20b29171c14e5ae759beb26a849426f6961
