Add a new beta feature - share icon. When user opts into beta
the share icon will be visible on supported devices (Android OS
and Chrome browser).
Bug: T181195
Change-Id: Ie4b9dd05eea9b63422bd174048d8b1251cb02bf4
It's presumed that skin options will eventually become the default or be removed from the skin.
While they are not the default, it would be helpful to package them in one single module - as ResourceLoader
modules are costly bloating the dependency graph in the MediaWiki startup module.
In T167713 we talked about grouping our entry points by page rather than feature, which this seems consistent
with. A page with special options enabled is different from a page without.
Change-Id: Id948f913d4743532ba3442d2059a03c122419ff2
