Media views EmbedLink debounce

[afercia]

Not sure the current usage of _.debounce is correct when embedding a link from "Insert from URL". To my understanding, the updateoEmbed function should not be debounced and fetch should be debounced instead.
See discussion about _.debounce on #26600

[wonderboymusic]

_.debounce is correctly placed on the typing callback. The real issue is stampede of XHRs on fetch(). These aren't necessarily a problem, but the browser shouldn't try to handle all of them.

If a fetch() is happening, and another one is triggered, the currently pending XHR should be aborted. You can't call abort() on $.Deferred, but you can on $.ajax, so we will use that instead of wp.media.ajax, which returns a deferred Promise.

[wonderboymusic]

In 32460:

When fetching in media/views/embed/link.js, call abort() on any existing XHRs.
Use $.ajax instead of wp.ajax.send() to allow this.
Pass this as context to the options to remove the need to bind callbacks.

Fixes #32035.