Get UI language names (autonyms and names of languages in other languages) from SLDR

[tombogle]

User Story
As a user, consultant, or support person, I want to be able to see the UI language list in both the autonym of the language and in my current UI language (or English if not known).

Description
Currently this information is spottily available via a hard-coded set of data.

Implementation idea
Much of this information should available (and more authoritative) via SLDR, so it would be best to get it from there.

Testing ideas
When this is done, it should be possible to see, for example, the autonyms for the two Chinese variants in the UI language dropdown in Settings.