ImagePage: Make metadata table's initial collapse CSS-only
Make the initial collapse of the metadata table not depend on
JavaScript. This eliminates the FOUC, and will also reduce JS
footprint once compat can be removed.
* Move the 'display: none;' styles from metadata.css to
filepage.css so that they are part of the base styles for
file pages (metadata.css is only for supporting metadata.js,
which is loaded dynamically).
* Apply "collapsed" class from the PHP side immediately,
instead of calling "addClass" in JavaScript.
* Restrict hide-styles to only apply under .client-js to make
sure the rows remain visible in no-js mode.
* Declare dependency between metadata.js and filepage.css.
This is just for documentation purposes, as they are both
already separately loaded on all file pages.
Change-Id: If22bf7acb47b59151dc3b0843a62507c100e548b