This adds the pw_polyfill bazel targets that can be consumed by a
remote toolchain. This change also adds a dependency on a set of remote
toolchains that target both host and ARM cortex-m devices. The remote
toolchain is compatible with the bazel targets in pw_polyfill.
Change-Id: I868d3349d8c20a70725e6f936cd6ca54acd93ef3
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/32820
Reviewed-by: Keir Mierle <keir@google.com>
Reviewed-by: Wyatt Hepler <hepler@google.com>
Reviewed-by: Akira Baruah <akira.baruah@gmail.com>
Commit-Queue: Wyatt Hepler <hepler@google.com>
