update_dictionaries: cache and speedup and fixup
Rather than download the archives fresh everytime, cache them locally
in a cache/ dir. This makes repeat runs faster and easier to update
just one language in here.
Disable uk_UA fetching for now as the URL no longer works and I can't
find an obvious replacement.
Move the file renaming logic outside of the download+unpack loop since
we only need to run this once per run, not once-per-file. They all
have unique non-conflicting names so we don't have to worry about one
2 files changed