@types/bun: deprecate some unused types especially on Bun ns

[Elusive7733]

What does this PR do?

Mark unused types as deprecated to improve type clarity and documentation:

• Add deprecation tags to event listener types (BeforeExitListener, etc.)
• Deprecate FileBlob with direction to use BunFile instead
• Replace XMLHttpRequestBodyInit with expanded type definition in fetch.d.ts

• Documentation or TypeScript types (it's okay to leave the rest blank in this case)
• Code changes

How did you verify your code works?

[alii]

There are a few more types that should be removed, I think the real fix for this is figuring out a more reliable way to detect these unused types.

Additionally could you please remove the symbols from bun.d.ts that you added to deprecated.d.ts, otherwise they are declared twice.

[Elusive7733]

making changes.

Also we can create a script or that can detect all unused types to deal with this in the future.

[alii]

Yeah, exactly. A script to detect these would be perfect. I'm not immediately sure how it would behave. Would need some investigation.

[Elusive7733]

Hi @alii I have addressed the comments and I am also am working on a script that auto detects unused types.

I think the PR for the script should be a different one, also there are a few edgcases with the script that needs to be considered.

For now / going forward we should probably add an eslint rule for unused types.

[alii]

Cool, thanks! I agree, a lint rule would be nice.

Currently busy with some work on the Bun website right now, but I will pull this branch and make sure everything works as expected later today.

[Elusive7733]

@alii Are you planning to merge this ?

Also can you point out more good first issues that I can pick up.
Looking forward to contribute to bun.

[alii]

@Elusive7733 Looking through at the moment, couple of things I'll update myself on this (your) branch. We will/can probably merge this soon. Thanks again for the contributions.