Basic zoom functionality for the cutting view

[Arnei]

Based off of the subtitle view. Implements a very basic zoom functionality, hoping that it's better than nothing. Includes:

• A Slider to control the zoom level
• A horizontal scrollbar to move the timeline
• Drag n' Drop to move the timeline

Known issues:

• ~The scrubber/playhead is cut off if placed either at 0 or at the maximum duration. I might have css'd myself into a corner here.~

Possible future feature extensions:

• Hotkeys
• Centering the zoom on the scrubber/playhead while zooming in (difficult to do without jittering)
• Configuration

Resolves #107.

Courtesy of the Opencast 2023 Crowdfunding.