Enhance Bilibili video support (redo of #2522) (#2599)

* Enhance support for bilibili videos in responsive video helper, and add corresponding doc

* Apply @iBug's review in mmistakes/minimal-mistakes#2522

* Fix danmaku in page hero video

* Update video to use case..when for iframe src

* Update CHANGELOG and history

Co-authored-by: Anran <51769728+ALeafWolf@users.noreply.github.com>
Co-authored-by: Michael Rose <mmistakes@users.noreply.github.com>

Update CHANGELOG and history

Update CHANGELOG and history

Update CHANGELOG and history

Update CHANGELOG and history

Load Font Awesome CSS from jsDelivr CDN (#2583)

* Load Font Awesome CSS from jsDelivr CDN
* Update CHANGELOG and history

Update CHANGELOG and history

Update CHANGELOG and history

Update GreedyNav.js

Replace custom comment hardcoded HTML with include

Also add custom_scripts.html include for custom comment provider JavaScript that loads in the footer.

Close #2549

Update CHANGELOG and history

Update CHANGELOG and history

Reword commit change

Make sticky sidebar live well with short content (#2514)

Fix typo

Release 4.19.2 💎

Update CHANGELOG and history

Update CHANGELOG and history

Update CHANGELOG and history

Update CHANGELOG and history