Add optional languageId to window.createOutputChannel API (#19561)

[John Murray (gjsjohnmurray)]

This PR fixes #19561 by implementing proposed API which adds an optional languageId param to window.createOutputChannel.

This was previously suggested by Artem Govorov (@ArtemGovorov) and was supported at the time by Johannes Rieken (@jrieken).

It was later raised as a solution for #19561, opened by Jun Han (@formulahendry).

[John Murray (gjsjohnmurray)]

Sandeep Somavarapu (@sandy081) any chance you could consider merging this in time for Monday's endgame?

[Sandeep Somavarapu (sandy081)]

I am sorry that I have to postpone this for the next milestone as this has to be discussed in our API sync meeting first. The last API sync for this milestone finished today and unfortunately I missed checking this in time. Since there is no urgency, I will plan this for next milestone and discuss in our API sync.

[John Murray (gjsjohnmurray)]

Sandeep Somavarapu (@sandy081) no worries. I know you have been busy with other things.

[John Murray (gjsjohnmurray)]

Sandeep Somavarapu (@sandy081) now that 1.64 has shipped, when will the next API sync meeting happen? I'd like to get this into Insiders soon.

[Sandeep Somavarapu (sandy081)]

John Murray (@gjsjohnmurray) Thanks for reminding. API call is today. As per the process we will first add it to the proposed API and after getting some feedback we will finalize it. So most probably this will be a proposed API in this month and goes into finalization next month.

[Sandeep Somavarapu (sandy081)]

Changes look good. Did some small clean ups. Approved.