Currently each locale is fetched serially, which means the user must wait for MANY roundtrip HTTP calls to start and complete.
Since each locale file is relatively tiny, fetching them all in parallel results in a near-instant startup time and the user can see the installation modal much more quickly.
Since I was here I deduplicated all the redundant lines so new locales can be added much more easily.
This more compact form also helps eliminate certain classes of bugs. I noticed that all the licenses were actually being fetched twice, likely due to copy-paste human error.
