Adopt getAllModels

[m-nash]

Tasks

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1. Remove alias model in getAllModels typespec-azure#300 block all alias models cases
2. [Bug][getAllOperations]: alias model is not calculated typespec-azure#69
   bug getAllOperations lib:tcgc +3
   
3. [Bug][TCGC] Enum used in decorator is not calculated typespec-azure#128 block cases where enum value is used in decorator
4. [Bug][TCGC] __raw property is null if it's an implicit discriminator property typespec-azure#201
   bug lib:tcgc +2
   
5. [Bug][getAllModels] OperatoinStatus not found even filter-out-core-models : false typespec-azure#204
   Blocking bug getAllModels lib:tcgc +4
   
6. [Bug][TCGC] Multiple instances of OperationStatus model definition typespec-azure#346 block LRO
7. Implement TCGC's Model Types #4539
   DPG duplicate +2
   
8. [Bug][TCGC]: Incorrect discriminator value of discriminator property if it's union type typespec-azure#676
   Blocking bug lib:tcgc +3
   
9. [Bug]: getDiscrminator return undefined while TCGC can find the discriminator microsoft/typespec#3184
   bug needs-area needs-info +3
   
10. [Bug][TCGC 0.41.4]: discrminiator property type usage should be RoundTrip typespec-azure#723
    bug lib:tcgc needs-area +3
    
11. [TCGC][Bug] getAllModels, Optional literal do not have correct generated name typespec-azure#553
    getAllModels lib:tcgc +2
    
12. [Bug][TCGC 0.41.4]: @clientName not work typespec-azure#730
    bug lib:tcgc needs-area +3