scap php: New subcommand
This commit add scap php, which is like scap mwscript but will run
without using multiversion/MWScript.php. This is useful for unusual
situations like in train-dev's create-databases script which needs
to run install.php.
Related MRs:
- !871 (merged)
- !870 (merged)
- !859 (merged) (This MR)
- master