[DRAFT] feat(ext/fetch): Implement EventSource

[MierenManz]

closes #10298
This still needs some work.

• update WPT expectations
• Use Primordials
• Use Ops instead of fetch
• Use Symbols
• Typings
• Add to 99_main.js

[CLAassistant]

All committers have signed the CLA.

[MierenManz]

if you have any constructive feedback. Feel free to comment 😉

[crowlKats]

Typings are missings, loading in 99_main missing, don't use private properties but symbols.
Also dont see any need for the webidl dict being a variable and then assigned to the converter, could just inline that.

[lucacasonato]

Some comments:

• This needs to be changed to use primordials. No globals should be used.
• This should not depend on the fetch function. Instead op_fetch* ops should be used directly, or the event source parsing should be moved to Rust (i.e. op_eventsource + op_eventsource_next).

[MierenManz]

I think I'll go the op fetch route. I don't really see the need to do this stuff in rust.

[stale]

This pull request has been automatically marked as stale because it has not had recent activity. It will be closed in 7 days if no further activity occurs. Thank you for your contributions.

[MierenManz]

This is quite a messy PR. So I've talked with @crowlKats and decided that I'm gonna implement this from scratch rather than trying to fix this PR. I will open that hopefully today or tomorrow