Remaining properties naming polishes

[Manishearth]

Carried over from #1239

With #2140 and #2112, the main icu_properties return values are all consistently named. We have CodePoint[Set|Map]Data(Borrowed)? as a naming scheme for the main APIs for interacting with this data. Stringy maps and sets can be supported in the future with [Unicode|CodePoint]{Set|Map]Data(Borrowed)?

So far, the data structs have not been renamed. They're currently called UnicodePropertyV1 and UnicodePropertyMapV1, which isn't great. Note that these types are not super important since users shouldn't be interfacing with them, but consistent naming woudl be nice.

@echeran suggested Property[Unicode|CodePoint][Set|Map]V1. I like having Property in the name there.

Also we have UnicodeSet. I don't think we need as much consistency there: that's a specific backend and doesn't need to be named analogously to other backends, but we probably should name it CodePointSet or something (and rename the builder type and associated methods).

[sffc]

Renaming UnicodeSet to CodePointSet should be done at some point, either as a standalone PR or as part of the migration to icu_collections.

[andrewpollack]

For this, I'll create two PRs:

1. Renaming UnicodePropertyV1 -> PropertyUnicodeSetV1, and UnicodePropertyMapV1 -> PropertyUnicodeMapV1
2. Renaming UnicodeSet -> CodePointSet, and all related libraries. This will be done before the migration to icu_collections

[sffc]

@andrewpollack Is this complete?

[andrewpollack]

Completed by #2198