bp2build: migrate export_{,system_}include_dirs -> *includes for...

bp2build: migrate export_{,system_}include_dirs -> *includes for cc_prebuilt_library{,_static,_shared}

Migrate `export_include_dirs` property to attribute `export_includes`, handling arch/os-variants
Migrate `export_system_include_dirs` property to attribute `export_system_includes`, handling arch/os-variants

Test: cc_prebuilt_library_{,shared_,static_}conversion_test.go
Test: mixed_droid.sh
Bug: 229374533

Change-Id: I658a336a71265af0545c1c2db1a4f6eb613a7366