[bazel] Add Bazel-only GM for testing purposes.

Motivation: See comments in //gm/hello_bazel_world.cpp and follow-up CL: https://skia-review.googlesource.com/c/skia/+/747957.

Bug: b/40045301
Change-Id: Ic88d3636548939fadef72901e1cb46c0882bb42a
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/747956
Auto-Submit: Leandro Lovisolo <lovisolo@google.com>
Reviewed-by: Kevin Lubick <kjlubick@google.com>
Commit-Queue: Leandro Lovisolo <lovisolo@google.com>
5 files changed