Consolidate AdditionalProperties with raw data field (Phase 1)

[ArcturusZhang]

Fixes #4128

For phases, please refer #4465

Description

1. Support the ...Record<T> syntax for additional properties.
2. Update the serialization code so that now when we have additional properties of primitive types, when invalid value comes in, we no longer throw exceptions.

Main changes in the generator:

1. some changes in the emitter to support ...Record<T> syntax for additional properties. I think we do not have to have a perfect solution for that because the perfect solution for this is adopting getAllModels from TCGC, therefore that change is just making it work.
2. I changed the JSON serialization to contain two things: an AdditionalPropertiesSerialization and a RawDataFieldSerialization since a model might have both when its additionalProperties property cannot catch everything up.

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