Add Bazel-viewer-Mac job to CI

I chose the M4 macs as a target because they were the newest/
fastest we had. It was a bit tricky to get a bazelCacheDir
because we didn't have write permissions in the "usual" places
like /opt or /home, so, I put it under the Swarming Work directory.

Bug: b/256860816
Change-Id: I20f9725aff8d74f05005d97eeeb2cfc2075bf3f9
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/1155556
Reviewed-by: Eric Boren <borenet@google.com>