[FEATURE REQ] investigate enable stream serialization for mgmt

[weidongxu-microsoft]

Is your feature request related to a problem? Please describe.
Relate to #38569

Pending investigate whether mgmt can have stream-style-serialization turned on.

Potential issue:

• Some class in azure-core-management needs update to impl the interface.
  • Alan's PR Support azure-json in azure-core-management #38322
• There could be bug involved with weird mgmt SDK.
• The flatten solution in mgmt may affect.

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Tasks

Beta Give feedback

1. mgmt azure-json, fromJson cannot access read-only property from Resource autorest.java#2740
   Mgmt +1
2. [FEATURE REQ] mgmt azure-json, SubResource need to implement JsonSerializable interface #40047
   Azure.Core Mgmt +2
   
3. Inner classes' validate() method implementation wrongly calls super.validate() on Resource/ProxyResource which doesn't have validate(). #40409
   needs-triage +1
4. mgmt azure-json, in fromJson, sub class cannot call package-private setters on read-only properties of child class that's in a different package autorest.java#2741
   4 of 4
   Mgmt +1
   
5. mgmt azure-json, flatten property in parent class will cause issue in child class in a different package autorest.java#2742
   0 of 5
   Mgmt +1
   

[alzimmermsft]

I believe #38322 is related to this as well