mitigate breakings for CLI when adopting Python SDK which migrates to typespec from swagger

[msyyc]

issues that CLI meet when adopting Python SDK which migrates to Typespec:

• {Core} Adopt serialization func from azure-core for CLI's todict formatting azure-cli#31775
• {Core} Add dict transformation for typespec generated SDKs azure-cli#30339
• CLI meets output breaking when migrate to new SDK generated from Typespec microsoft/typespec#9004
• [python][bug] compatible logic for flatten doesn't work for model initialization microsoft/typespec#8994
• suffix _property for model property causes unexpected breakings for Azure CLI microsoft/typespec#9013

[msyyc]

https://gist.github.com/msyyc/648ed3d400f7bb799a647c89c2c80e41

[msyyc]

keyvault migration PR : #43559

[lirenhe]

close it as completed.