Enhancement for the Addon Manager

In an experimental Addon Manager, added a language code override.

I tried having Claude build a menu of languages. But it failed to list anything but en as an option. So you just have to type in the override language code in the Edit Project dialog. Then click the Refresh button afterwards to force a re-read of the override .json file.
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The .json , listings folder and testing URL are all hot-linked to make manual inspection easier.

So while running the English GUI of Gramps, I can “override” to review the “da” (Danish) list of updates: