Disable language selection for everything other than English GB (#4467)

# Description of Changes
For the first release of V2, we'll not have any reasonable translations
for anything other than English GB, so with that in mind, this PR
disables language selection for anything other than English GB, with a
tooltip saying the other languages are coming soon. I also split the JSX
up a little bit while I was at it to make it easier to manage.

---------

Co-authored-by: EthanHealy01 <80844253+EthanHealy01@users.noreply.github.com>