Handle product config specific header_libs prop in cc bp2build

Product variable header_libs is able to be converted.
Since static_libs and header_libs both use implementationDeps,
also added logic to make sure they both contribute to bazel
target.

Bug: 228314770
Test: m bp2build
Test: TestCcLibraryProductVariablesHeaderLibs in cc_library_conversion_test
Change-Id: I370fc75b666b3908b6ac5ed42bca5560f957fc42