Make it easy/obvious to debug Unity editor batch mode

The current "Standalone Player" run config is expected to be used to debug players, but can also be used to debug the editor. The primary usage scenario is to debug players, hence the name, but there is no other easy way to debug the editor running in batch mode, with the `-batchmode` command line argument. The majority of use cases for debugging the editor are already covered by the existing "Attach to Unity Editor" and "Attach to Unity Editor & Play" configurations.

We should consider:
1. Renaming "Standalone Player" to something that can obviously debug both players and the editor, or
2. Introduce a new run config that is functionally the same as "Standalone Player" but is obviously intended for launching the editor. This could include config UI that provides the path to the executable based on already discovered Unity instances, and possibly adding the `-batchmode` argument by default.