Expose wrapper for ctx.actions.run() and ctx.actions.run_shell().
Expose wrapper for ctx.actions.run() and ctx.actions.run_shell().

Just like apple_action, provide helpers to use the two commands but
forcing them to happen on darwin.

RELNOTES: None.
PiperOrigin-RevId: 174314393

bazelbuild/rules_apple,bazelbuild/rules_apple,bazelbuild/rules_apple,bazelbuild/rules_apple