Namespace refactoring Implementation

[lmazuel]

No description provided.

[weidongxu-microsoft]

epic

• Support multiple namespaces in client library code generation microsoft/typespec#4537

design

• https://gist.github.com/srnagar/a695faa1a4d8a5dbf44af826f05916f0

depends

• [tcgc] namespaces in TCGC typespec-azure#1604
• [tcgc] provide a name for SDK client (when SDK client is from TypeSpec Namespace) typespec-azure#1737
• fix in typespec about the namespace of template instance (it should be of the namespace of where instantiation take place)

[weidongxu-microsoft]

Java design (base on TCGC .namespace)

Azure

• Client classes would be under <tcgc_namespace>
• Model/enum classes would be under <tcgc_namespace>.models
• Internal model/enum classes would be under <tcgc_namespace>.implementation.models

This is following best practice on Azure Java Guideline e.g. model types, without service had to define a separate TypeSpec namespace for TypeSpec models.

Unbranded

• Client/model/enum classes would be under <tcgc_namespace>
• Internal model/enum classes would be under <tcgc_namespace>.implementation (?)

[weidongxu-microsoft]

Migration plan for Azure

• namespace option would override the client namespace from TCGC
• new onboard should not have namespace option
• migrate existing lib, update client.tsp to add @clientNamespace, and remove namespace option