Replace video.js with native HTML5 Video

The nuxeo-video-viewer element is currently using video.js but we have multiple reports of crap perfomance in Web UI for Video documents.

Other problems:

• we are stuck in v5.2.x (most recent version is 6.8.0) because video.js decided to drop bower support for >= 6
• as soon as v7 is released, v5 will reach end of life

  When Video.js 7 is released it’ll be the end-of-life for Video.js 5.x from a support perspective

HTML5 native video is supported across all browsers and will likely solve many reported issues (see linked issues). w3schools gives a good overview of supported browsers and supported formats for each browser.

The video player in each browser has a different look and feel, but if it's really important to have a single L&F, we can always disable the native controls and build a skin on top of it.