Set site logo url in ResourceLoaderSiteModule instead of inline styles

Requires skins to use the 'mw-wiki-logo' class on the logo element
for the styles to apply. This is backwards compatible with skins
not using that class and using inline styles instead.

Bug: 56257
Change-Id: I89e32fcd27c9f07e889aa5b67d7d97d06b412aea
Merge "Set site logo url in ResourceLoaderSiteModule instead of inline styles"