Rewrite requestMIDIAccess to hook into permissions

[miketaylr]

As a followup to #219 (review)

[cwilso]

What remains on top of #294?

[miketaylr]

Sorry for not writing a better description!

Essentially, https://webaudio.github.io/web-midi-api/#dom-navigator-requestmidiaccess needs to hook into the Permissions algorithms.

@marcoscaceres wrote some more explicit suggestions in #219 (review).

[miketaylr]

I will attempt to not mess this up.

[hoch]

Teleconference 4/6:
Remove "particularly if system exclusive access is requested." in the second paragraph of https://www.w3.org/TR/webmidi/#requestmidiaccess.

[miketaylr]

I will attempt to not mess this up.

(It looks like I never finished...)

[hoch]

No worries! We'll take it from here. :)

[miketaylr]

Yay, thanks! I'll go ahead and close my WIP PR now.

[mjwilson-google]

Audio WG 2023-10-18 conclusion:

• In the section https://webaudio.github.io/web-midi-api/#extensions-to-the-navigator-interface, instead of taking a MIDIOptions it should take a MIDIPermissionDescriptor
• We should also probably link the definition of Powerful Feature

[mjwilson-google]

I think changing the requestMIDIAccess API has compatibility risk. I will raise this again at the next working group meeting.

[mjwilson-google]

Specifically, there are three options I see:

• Add a new API that takes a MIDIPermissionDescriptor and remove the old API.
• Add a new API and deprecate the old API (potentially keeping the deprecated API forever).
• Don't add a new API and just continue to use the old API with the MIDIOptions dictionary.