Add RBE support for Atest Bazel mode to run tests on RBE
This change is implemented by following instructions at https://github.com/bazelbuild/bazel-toolchains/blob/master/README.md.
Example usage:
```
atest-src <test module> \
-c -v --host --bazel-mode \
--bazel-arg=--config=remote \
--bazel-arg=--remote_instance_name=<your rbe instance>
```
Test: atest-src HelloWorldHostTest -c -v --host --bazel-mode --bazel-arg=--config=remote --bazel-arg=--remote_instance_name=projects/pesto-rbe/instances/default_instance
Test: atest-src atest_unittests -c --host --bazel-mode
Change-Id: I316f6f555cb0fb46f3cd9a5e297126adf35637f9
5 files changed
