[bazel] Move test runners under //tools/testrunners.

The goal of this CL is to consolidate all code related to Bazel test runners under a single directory. This will facilitate navigating our code base as the test runners grow larger and share more code.

As discussed offline, this CL also renames:

- BazelTestRunner.cpp to BazelUnitTestRunner.cpp
- BazelGMRunner.cpp to BazelGMTestRunner.cpp
- BazelBenchmarkRunner.cpp to BazelBenchmarkTestRunner.cpp

Per our discussion, we agreed that "VisualTest" is more meaningful and less jargony than "GMTest". I tried renaming BazelGMRunner.cpp to BazelVisualTestRunner.cpp, but the fact that there are references to the notion of GMs everywhere made it feel inconsistent. I still prefer "VisualTest", but maybe we should do that rename as part of a larger rename after which "git grep -i gm" yields 0 relevant results. We will probably want to wait until after the migration from DM / nanobench to Bazel is complete.

Bug: b/40045301
Change-Id: I246dda522a7d2d424daaf0bf04e743ccf7c4b61c
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/765076
Commit-Queue: Leandro Lovisolo <lovisolo@google.com>
Reviewed-by: Kevin Lubick <kjlubick@google.com>
45 files changed