[Unbranded Client CodeGen] Emitters should ignore the unsupported authentication

[lirenhe]

Clear and concise description of the problem

We need to ignore the unsupported authentication defined in TypeSpec instead of generating incorrect code.
There is no plan to update the spec to remove those authentications.

Tasks

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1. ignore cookie authentication Azure/autorest.python#2938
   +0
   
2. http-client-java, skip ApiKeyAuth if not ApiKeyLocation.header #5182
   emitter:client:java +1
3. Unbranded CodeGen should ignore the generation of unsupported authentications Azure/autorest.typescript#2933
   HRLC non-azure p0 +3
   
4. [http-client-csharp] It is incorrect that OAuth2 authentication defined in the spec is silently ignored #5301
   emitter:client:csharp +1
   
5. [http-client-csharp] cookie auth is generating incorrect code #5302
   emitter:client:csharp +1
6. [http-client-csharp] CSharp Emitter should find a better way to handle unsupported authentication #5355
   emitter:client:csharp +1
   

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• Check that there isn't already an issue that request the same feature to avoid creating a duplicate.

[ArcturusZhang]

I kind of think the Ignore in the title is inappropriate - we should never "ignore" something, this is not a correct behavior.
Instead, we should not panic or crash when we met into something we cannot recognize.

[jsquire]

@lirenhe: I need this issue rescoped or a new one filed for C#, as it is not actionable in this form. We will need:

• A clear description of the problem that we're trying to solve. What are the troublesome scenarios? What is the experience that we're trying to offer? What is the scope of the problem?

• Something that identifies workstream this request is associated with. I believe this one is related to the VSCode extension, but that is just my assumption as that information is not available.

• Who are the stakeholders asking for this? We'll need to be able to work with them for additional information and to set expectations.

• What is the requested priority to associate with this?

• What is the requested timeframe for this? What does it block if it does not meet that requested timeframe?

We'll need the same information for all of the asks on the C# emitter in order to prioritize, resource plan, and execute.

//fyi: @JoshLove-msft, @m-nash, @ArthurMa1978, @lmazuel, @schaabs

[lmazuel]

@jsquire

• This about cookie auth and no auth applied to a sub namespace. The need is to ignore them (no crash)
• This is the E2E demo https://github.com/allenjzhang/typespec-e2e-demo/tree/main, not related to VSCode
• Allen and Laurent :)
• P0
• Mid-January 2025. Again, this is just "ignore, don't crash". It blocks the demo meeting planned for mid-January to showcase we're on track for E2E experience for the TypeSpec GA

[lirenhe]

@jsquire, I created a separate issue for .NET here. #5355