Add more fetch keys

[autonome]

No description provided.

[Elchi3]

My review approach here is a comparison against the burndown of non-deprecated and standardized BCD keys for the interfaces mentioned and so I found more keys to consider here. But it could also be that some keys want to live in a separate feature or already do, so take the suggestions as inspiration rather than blockers.

[autonome]

My review approach here is a comparison against the burndown of non-deprecated and standardized BCD keys for the interfaces mentioned and so I found more keys to consider here. But it could also be that some keys want to live in a separate feature or already do, so take the suggestions as inspiration rather than blockers.

this is great, thanks! i found the additional keys in this PR... somewhere (?), so added them. definitely will add these others and see what it looks like.

[autonome]

Aha i see your other patch now! I'll limit this to fetch, so we don't conflict, and you can do all the xhr additions in #1963.

[autonome]

added all, looks good, thanks @Elchi3!

[autonome]

Did a pass to see if any of these keys should be separate features.

Caniuse doesn't break any sub features out, just has Fetch and shows the baseline high widget.

There's a multi-year trickle of additions for blob support, readable stream integration and misc bits and bobs, some of which are baseline false.

There's nothing that seems to stand out from the implementation timeline, nor from the docs or dev comments/writing based on the searches I did.

There aren't any keys that match the other sub-features (metadata and priority).

So leaving it all in here for now.

[Elchi3]

Nice, this looks good to me. Great to see all ducks in a row for fetch. I think we can always move stuff out into a separate feature later if there is appetite.