[TCGC] introduce cache for model properties

[ArcturusZhang]

Unlike other types, we have cache in TCGC, such as SdkModelType, etc.
This ensures us if we put the same instance of Model from compiler, we always get back the same instance of SdkModelType.

We should introduce cache for model properties as well, now every time we give the same ModelProperty into getSdkModelPropertyType, it gives back a new instance every time.