[TCGC] Initial Adoption of getAllModels()

[archerzz]

Description

As a pre-requisite of #3994, we should first adopt getAllModels().

Describe your ideas for solutions
Leverage closed PR (#3627). Ideally, we should be able to just convert return value of getAllModels() into input types. But the model hierarchy of TCGC could be slightly different from model hierarchy generated by csharp emitter. So, we'd better first just use getAllModels() as a source of models when iterating operations/models in the emitter.

[archerzz]

close since it's a duplicate of #4300