feat(tcgc): use `@server` description for default `endpoint` client parameter

[archerzz]

Clear and concise description of the problem

This is a minor issue.

See cadl-ranch server definition: https://github.com/Azure/cadl-ranch/blob/2fb006d5b4609647138382bf5d248a2edbde7742/packages/cadl-ranch-expect/src/decorators.ts#L241 There is no parameter defined for endpoint, instead it's a hard-coded value.

context.call($server, target, "http://localhost:3000", "TestServer endpoint");

TCGC will give a default endpoint parameter with description Service host. Maybe we should use the description defined in @server? e.g. for this case, it's TestServer endpoint.

Checklist

• [X] Follow our Code of Conduct
• [X] Check that this issue is about the Azure libraries for typespec. For feature request in the typespec language or core libraries file it in the TypeSpec repo
• [X] Read the docs.
• [X] Check that there isn't already an issue that request the same feature to avoid creating a duplicate.

[archerzz]

Maybe we should differentiate a constant endpoint URL case from an expression endpoint URL case. For endpoint which is an expression, it would be better that each template argument description is undefined? (it doesn't make sense to assign service description to them)

@server(
    "{firstTestTypeSpecUrl}",
    "Endpoint Service",
    {
        firstTestTypeSpecUrl: string,
    }
)

[archerzz]

Another example of why we might need to leave uri template parameter as-is:

[archerzz]

We have further discussion, and we thought it might be better to just leave description empty if it's not defined. And let each language emitter to decide what they want to add.