JS emitter should derive `Accept` header parameter from the response content-type

[jeremymeng]

https://developer.mozilla.org/en-US/docs/Web/HTTP/Reference/Headers/Accept

the generated code should send a list of content-types that it can handle to the service.

[joheredi]

This is already how it works, TCGC derives this for us. The problem here seems to be that core is adding application/json by default when no Accept header is set. This will be a problem when there are operations that expect no response body, hence there is no Accept value to be derived.

For this one we should ignore the header in the recordings, and have a fix in core to not fill this out by default, maybe through an overload to avoid breaking changes.

[lirenhe]

@joheredi, will you take care of this item? thanks
From your description, it seems to be a core issue to handle the header when there is no response body.