All actions which use tool or executable for which is not clear if it comes from a toolchain, must set a `toolchain` parameter ( migration of Automatic Exec Groups).
As we discussed internally, I've modified actions so that it's recognised that tools are not from the toolchain. Hence, there will not be an error which states `Couldn't identify if tools are from implicit dependencies or a toolchain. Please set the toolchain parameter. If you're not using a toolchain, set it to 'None'.`. Hence, no need for the toolchain parameter.
* Create a helper rule for selecting a file from outputs of another rule or a filegroup by subpath
* Add tests
* Address code review comments
* + formatting
Co-authored-by: c-parsons <cparsons@google.com>
Alexandre Rostovtsev