Bug 44959: Allow overlay heading title to span 2 lines

As raised in bug 44959,
In some languages it is not 1 line. This fixes up the header so that
the padding belongs to the header itself meaning the title will never
overlap the 'hamburger' left menu button

e.g. Special:Mobileoptions

See
https://translatewiki.net/wiki/Thread:Support/About_MediaWiki:Mobile-frontend-main-menu-settings-heading/en

Change-Id: I27c719e85ba3e1c29891b2bf74d971bb433c2f5c
Merge "Bug 44959: Allow overlay heading title to span 2 lines"