Add time information to video controls and timeline

[marktaipan-cvisionai]

Add ability to obtain and navigate videos using relative time (and UTC time if available) in the annotation-player and annotation-multi elements. This updates should apply to both the video player controls and the timeline-d3 axis (e.g. changing the units used by the timeline).

[bctcvai]

FYI, this new issue is better worded, but when we close this let's also close: #506