Add support for Better Video Scrolling

[anthonypkeane]

Description:

Tapping on the video scroll bar should take you to that position on the video/audio file.

[stephendonner]

Verified PASSED using Brave build 1.27 (21.6.15.14) on iPhone 6s, iOS 14.4.2.

Steps:

1. new install
2. launched Brave (dev)
3. loaded youtube.com
4. searched for never gonna give you up
5. played video
6. added video to my Playlist
7. tapped Open when prompted to open in Playlist
8. (regression-test) confirmed I was able to seek the video with the slider/progress bar traditionally, by tap, hold, and drag motions
9. confirmed I could tap on a position on the slider/progress bar, and the video jumped and resumed playing from there; tried in both landscape and portrait orientations/modes

rick-roll.MP4