[bazel] SkCMS RBE config for Windows.

After this CL lands, it will be possible to build and test SkCMS under Windows RBE by running the following commands:

    > bazel build //... --config=windows-rbe
    > bazel test //... --config=windows-rbe

This CL is the Windows analogous to https://skia-review.googlesource.com/c/skcms/+/437918. See said CL's description for more details.

Note to reviewer: Files under //bazel/toolchains/windows-bazel-4.2.1 are generated.

Bug: skia:12400
Change-Id: I67b7e9a136ccce6386e4c34465d1a8a59f0bcc16
Reviewed-on: https://skia-review.googlesource.com/c/skcms/+/452361
Reviewed-by: Joe Gregorio <jcgregorio@google.com>
Commit-Queue: Leandro Lovisolo <lovisolo@google.com>
18 files changed