Language Refactor 3 (#937)

This significantly improves the quality of the language system by fixing
the mistakes I've made almost a year ago while developing it.

Mainly, this throws away the old half-broken way of networking in favor
of the component state system provided by RT. Language speaker comp is
now shared with SendOnlyToOwner = true, and its state is handled
manually.

In addition to that, this brings the following changes:
- UniversalLanguageSpeaker and LanguageKnowledge are now server-side
- DetermineLanguagesEvent and LanguagesUpdateEvent are now shared (so
that future systems can be built in shared, if needed)
- Everything now uses the ProtoId<LanguagePrototype> type instead of raw
strings (god, I hated those so much)
- The server-side language system now accepts Entity<T?> arguments
instead of EntityUid + T
- UniversalLanguageSpeaker is now based on DetermineEntityLanguagesEvent
and gets an Enabled field, which allows to turn it off. This may have
some use in the future.
- Some minor cleanup

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No cl

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Co-authored-by: VMSolidus <[email protected]>
(cherry picked from commit 8c5faf3)