Typespec renaming

[chunyu3]

Description

Fix #3196
Fix #3183

• upgrade typespec libraries to 0.41.0
• rename dotnet emitter to @azure-tools/typespec-csharp

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[lirenhe]

Do you plan to rename files also in this PR?
CadlGenerate.ps1 =>typespecGenerate.ps1

[lirenhe]

@chunyu3 Could you share the result of the SDK repo regen?
Any other failures besides OpenAI and MVAD?

[chunyu3]

@chunyu3 Could you share the result of the SDK repo regen? Any other failures besides OpenAI and MVAD?

Yes. I regened the sdk repo. There is no changes except failure on cadl dpg project OpenAI and MVAD.

[chunyu3]

regen azure-sdk-for-net, regen branch: https://github.com/chunyu3/azure-sdk-for-net/tree/typespecRenaming, no sdk change.

[lirenhe]

The rest of rename (file/folder, cadl.json etc )could be happen in another PR. Approve this one to unblock the migration effort.