Add shell helper to make it easier to execute `buildozer` commands on a repository

[cgrindel]

The current README.md states that the following should work:

bazel run -- @buildifier_prebuilt//:buildozer ARGS

However, this will not work correctly. Bazel will execute the command in a sandbox, not the workspace. Hence, buildozer will never find any of the paths.

A possible fix would be to provide a shell script that performs a cd "${BUILD_WORKSPACE_DIRECTORY}" and then executes the buildozer commands.

NOTE: The buildifier would also benefit from this technique as today one must specify absolute paths for buildifier to find files and directories.

[keith]

Ah yea, the only reason I didn't do a shell script before was because that seemed unnecessary, but yea this is a good reason

[manuelnaranjo]

BTW a shell wrapper is not needed at all:

alias(
    name = "buildozer",
    actual = "@buildifier_prebuilt//:buildozer",
)

Then here is an example execution:

$ bazel run :buildozer -- 'print actual' //:buildozer
INFO: Invocation ID: 3f4494b3-882e-4c28-a33f-2e37ccb33baa
INFO: Analyzed target //:buildozer (0 packages loaded, 0 targets configured).
INFO: Found 1 target...
Target @buildifier_prebuilt~6.0.0.1//buildozer:buildozer up-to-date:
  dist/bin/external/buildifier_prebuilt~6.0.0.1/buildozer/buildozer
INFO: Elapsed time: 0.192s, Critical Path: 0.00s
INFO: 1 process: 1 internal.
INFO: Build completed successfully, 1 total action
INFO: Running command line: dist/bin/external/buildifier_prebuilt~6.0.0.1/buildozer/buildozer 'print actual' //:buildozer
@buildifier_prebuilt//:buildozer