Add `getResourceLoaderStylesModules`

[osnard]

The ITag interface currently only has a getResourceLoaderModules method

https://github.com/hallowelt/mwstake-mediawiki-component-generictaghandler/blob/master/src/ITag.php#L35

It is used to load RL modules only on pages that have the tag.

https://github.com/hallowelt/mwstake-mediawiki-component-generictaghandler/blob/master/src/TagRenderer.php#L55-L58

Unfortunately, if the RL module contains styles, this may lead to a FOUC, as the RL module only gets loaded after the initial page load.