BLD-1230: Video Link Obfuscation

A contextual menu has been added to non-YouTube videos.

**Ticket: [BLD-1230](https://openedx.atlassian.net/browse/BLD-1130)**

**Acceptance criteria:**
When a student right-clicks on a video, they are not presented with any of the following options:
 * Save video as
 * Copy Video URL
 * Copy Video Address
 * Open video in New Tab
 * Open Video in New Window
 * Save Snapshot As….
 * Email Video
 * Copy Video Location
 * View Video
 * Download Video
 * Download Video As

When a student right-clicks on a non-YouTube video, they are instead presented with options for controlling the video including:
 * Play
 * Pause
 * Mute
 * Full Screen
 * Play Speed (with a sub-menu populated with the default speed options of the browser)

**Sandbox: [polesye.m.sandbox.edx.org](polesye.m.sandbox.edx.org)**