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Fixed issue with resolve buttons always being visible - even when not logged in

Store that manages the state of each button

Closes #19741

Handle videos in:
- MD preview in notes: commit, issue/MR, MR diff
- New notes in: commit, issue/MR, MR diff
- Persisted notes in: commit, issue/MR, MR diff
Signed-off-by: NRémy Coutable <remy@rymai.me>

* Registered video MIME types
* Currently supporting browser-supported formats with extensions that match the mime type

This reverts commit ec37d955.

This fixes an issue where the dropdown menu would stay visible even when clicked out of it

This reverts commit 530f5158.

See !4892.
Signed-off-by: NRémy Coutable <remy@rymai.me>

This reverts merge request !4970

fixies #19747

1. This scenario was previously tested for the registration flow, but
   not authentication.

1. According to the spec, either we have a single challenge with
   a number of `signRequests`, or a number of `signRequests`, each with
   it's own challenge.

2. Previously, we had both these - per-request challenges, as well as a
   single extra challenge.

3. This commit changes this so that the per-request challenges are
   removed, leaving only a single challenge, as per the v1.1 U2F API.

4. The existing implementation didn't work in Firefox, because the
   Firefox (extension) implementation is less flexible with regard to
   the inputs.

5. Fix teaspoon specs.

6. References: https://fidoalliance.org/specs/fido-u2f-v1.0-nfc-bt-amendment-20150514/fido-u2f-javascript-api.html#h2_background

1. Only on supported Chrome versions

2. Mainly, this lets us simplify the javascript-based U2F check to
   `window.u2f`, where `window.u2f` can either be loaded from the GitLab
   server (for Chrome) or from the Firefox extension.

3. This is a better way to provide browser detection for U2F.

This reverts commit 9ca633eb, reversing
changes made to fb229bbf.