Add .mw-editsection-like class, behavior same as .mw-editsection

Add .mw-editsection-like class, behavior same as .mw-editsection

The styling is neat and can be used for other purposes on-wiki
(examples include the {{Documentation}} template on the English
Wikipedia and the index of biographies at the Polish Wikipedia at
[[Wikipedia:Indeks biografii]]).

Since .mw-editsection is often used by scripts enhancing the links
(including VisualEditor and many gadgets) using it for other things
might cause unexpected behavior. Existing uses can now be easily
swapped for .mw-editsection-like.

Change-Id: Ic390c3047e5e6fd3a351d0ec1ca94ebef9367f6d