Implement fallback langauges

Return an array of languages instead of a single language. Languages
containing hyphens return themselves along with the root code e.g.
'en-GB' => ['en-GB', 'en']

Change-Id: I840b689d0021d865f93d16d075473a2ed0a9f0d8
Remove language variants from bold/italic now we have fallbacks

Bug: 53094

Change-Id: Id2328d6e7f89cd9deddde67b57cd7e3fc55683e6
Merge changes Id2328d6e,I840b689d

* changes:
  Remove language variants from bold/italic now we have fallbacks
  Implement fallback langauges