hopefully a surgical change. downstream packages (hls.js and dash.js)
are already drawn from the latest by default in mediaelement.js. based
on past WIP by @jason-raitz. refs [DP-796](https://ucblib.atlassian.net/browse/DP-796).

Co-authored-by: María A. Matienzo <[email protected]>
Co-authored-by: Jason Raitz <[email protected]>

* switches from class-based "automatic start" of MediaElement.js
instantiation to jQuery-based instantiation. this is necessary
as we need to pass dash.js configuration options in to prevent
it from rendering captions for us.
* add `crossorigin="anonymous"` to `<video>` tag to allow a
browser to load the webvtt file from wowza.lib.b.e.; otherwise
this would be a cross-domain request
* remove `default` from `<track>` tag to prevent captions from
showing automatically.

* add new helper methods to grab the URI for a WebVTT file included in a HLS manifest
* insert new <track/> tags specifically for HLS streams
* inject HLS.js configuration options to hide captions it renders

this will require setting the cupertinoVODCaptionsUseWebVTT property in all
wowza collections to true.

squashed refactors:

* refactor new hls vtt private methods in track extensions
* remove track tag for iOS as it is unnecessary

for iOS, it'll autodiscover the captions in the HLS stream when the viewer
is in its standard full-screen mode. the track extensions code that grabs
the HLS stream's WebVTT is thus unnecessary. this commits separates it out
in case it becomes useful in the future.