build: Make stylelint's grunt configuration like other extensions
build: Make stylelint's grunt configuration like other extensions

Move "options" out of "all", and have "all" just contain file paths.
While I'm sure this format works with grunt, this is how every other
extension has it configured and what LibUp's auto-fix code expects.

Change-Id: Ic376d9bc2f1a0664b8c59cd71a1f53f52eba7af3

wikimedia/mediawiki-extensions-Kartographer,wikimedia/mediawiki-extensions-Kartographer,wikimedia/mediawiki-extensions-Kartographer