Adds faster speed options (4x, 3x) to Echo360 player and allows the user to add their own speed options. Works on Chromium (Google Chrome, Brave, etc.) and Firefox
⚠ Note that there is a browser-set speed limit of 16x and speeds above 4x are muted, according to [the constants set in the brower's source](https://stackoverflow.com/a/32320020). This applies to both Firefox and Chromium.
- When setting `selected_speeds` to a list of speeds which does not include 1x, the player by default loads with 1x speed when the page is loaded. Once the speed is changed manually by clicking on a speed from the dropdown this is not an issue anymore, but it would be nice if the default speed was valid.