[Epic] mitigate unnecessary breaking between modular and hlc

[MaryGao]

See the diff pr: Azure/azure-sdk-for-js#28812.

Tasks

Beta Give feedback

1. Support client-level subscriptionId parameter #2348
   HRLC Mgmt p0 +3
   
2. Default endpoint and credentialScope setting for ARM is missing #2349
   HRLC Mgmt p0 +3
   
3. enum name is not normalizated in modular but in hlc #2350
   HRLC Mgmt p0 +3
   
4. Operation option interface is changed from DataProductsGetOptionalParams to DataProductsGetOptions #2352
   HRLC Mgmt p0 +3
   
5. user_impersonation is set as default credential scope in RLC #2353
   HRLC Mgmt p0 +3
   
6. title in tspconfig.yaml is not working in modular #2355
   HRLC Mgmt p0 +3
   
7. The user-agent is different between HLC and modular #2385
   HRLC p0 +2
   
8. Fail to set Content-Type in LRO polling url in modular but we have in HLC #2394
   HRLC p0 +2
   
9. The content type of put does not match in the recordings #2393
   +0
   
10. [Modular] Log warning/error for This client do not support client api-version #2427
    HRLC P1 RLC +3
    
11. [JS] Redesign Extensible Enum generation #2420
    HRLC RLC +2