Does not add `.mw-footer-*` CSS classes to `ul#footer-*` and
`li#footer-*-*` to save bandwidth.
NOTE:
- The former id selectors can be removed form the styles after the varnish cache
is updated with the new DOM.
- The modern version still uses the legacy layout at this stage.
Bug: T248137
Change-Id: Ica9f8c43617c624648fa12dc86ebb3daa10f0409
Going into the new version of Vector, we'll want to rewrite the layout
rules entirely and decouple the sidebar from the logo.
To prepare for this we will move the layout file into a legacy folder.
We also separate Sidebar styles needed for the legacy mode from the old mode.
This will allow us to make changes to the header in new Vector without having to touch
or test the legacy codebase via a new file layout.less and using the existing sidebar
code.
Bug: T246170
Change-Id: Ieb4f8f2b2f0e4f48d76a210ab30acd08e3e83bcb