Implement ZeroTrie dense data optimization in the data providers

[sffc]

Follow-up to #6920 and #3260

We now have a dense ZeroTrie, https://unicode-org.github.io/icu4x/rustdoc/zerotrie/dense/index.html

We should use it in data keys that benefit from it, especially display names and units.

See some discussion on the tradeoffs in #3260 (comment)

I consider this a graduation blocker for those components.