Add a new Wikitext editor with very basic formatting features
With this new editor, MobileFrontend get's some very basic editing
features to easier:
- add (or format existing) text to in bold or italic to the wikitext
- add a reference to the cursor position
The editor is sampled to 50% of wikitext editors and logged with the
editor name "SourceEditorWithFormatting" to EventLogging.
Depends on: Idd2275788f11303bd965994c9fb2e6c2d59daa33