[EDUCATOR-3262]

This reverts commit b9ebe5ea686fc1b16fccd0f276fbc1d53a5c3468.

EDUCATOR-3260

EDUCATOR-2606

another approach

There are other annotations features still in the platform but this one
is the one that works with an annotations server that was specialized
and not generally used by most instances of the platform.

The initial PR to remove this was made by 'lduarte1991' and can be found
here: https://github.com/edx/edx-platform/pull/17299

The work done based on the squashed commits:
removed advanced modules config for annotations
remove module files and config for annotations
remove js and css files related to annotations, under ova folders
removed js and css annotator file configs for cms and lms
remove template html files for annotations
removed annotations options from static html book
Added back some files that were originally marked "for OVA" but others used as per acceptance tests
Added back css file configs incorrectly marked as ova
Remove annotation related advanced settings from test.
Correct hls require.js pathing.

 The embedded video player does not allow the screen reader user to seek forwards / backwards within the time with the keyboard as you could in the past. If you tab to play a video and press spacebar or enter, you formerly would be able to press left / right arrow to move slightly forward or backward in time, but this no longer works correctly; it will move 1 second back / forward, then you need to press tab again to refocus and move another 1 second. Other keyboard access seems to be equivalent and we suspect a slight error in the Javascript is causing this and needs to be fixed.

EDUCATOR-3034

This reverts commit 105db2cf, reversing
changes made to 44745759.

These were very early experiments by the old performance team
on using CDNs for videos and logging performance data.  No one
is looking at this data and it's just extra cruft on every page.

This reverts commit 9a70ca78, reversing
changes made to efd5b9ab.

Hopefully fixes EDUCATOR-3053

This reverts commit 18d93b00.

Reapplies edx/edx-platform#17509

This reverts commit 0f7e2373.

The scroll lock class `modal-open` is removed from the body when the
EditImageModal is closed using the "Close" or "X" button, but not when the
"Insert Image" button is clicked. The submit button handler now calls the
`closeImageModal` handler too so that the `modal-open` class is removed after
inserting or editing an image.