Update BUILD and bazelrc for Bazel 9 based clients (#6218)

* Add load statements for build rules which used to be loaded automatically untill Bazel 8.x
* Use `--extra_toolchains` instead of `--cc_proto_library_header_suffixes` as this seem to have stopped working since `--incompatible_enable_proto_toolchain_resolution` is flipped to always on.
* Set `--incompatible_enable_proto_toolchain_resolution` so that clients on Bazel 8.x do not fail on  `--extra_toolchains`.


Tested by running extraction over Bazel and Gvisor's repo.