websocket: send/receive reducer & table ids instead of names (take 2)

[Centril]

Description of Changes

Receive and send reducer ids and table ids as opposed to names in the SDK.

Alternative to https://github.com/clockworklabs/SpacetimeDB/pull/1883 which is more efficient, but also uses indices internally rather than strings, making the diff larger.

API and ABI breaking changes

Yes.

[bfops]

@Centril is this both API and ABI breaking? Can you add the appropriate labels?

[CLAassistant]

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