Hybrid Replay Buffer

[derrod]

Description

Implements replay buffer using the Hybrid MP4/MOV muxer instead of FFmpeg.

Motivation and Context

• Feature parity with FFmpeg output
• Consistency between recording/replay buffer
• New features!

This implements a second hotkey as often requested (e.g. on Fider) that will dump the contents of the buffer after saving so two replay buffers saved back to back do not contain the same content[^1]

[^1]: Currently saving is allowed on non-keyframes, and discarding only happens up until the last keyframe. So there can be a few seconds of overlap still.

How Has This Been Tested?

Tested locally with both hotkeys and HEVC.

Types of changes

• New feature (non-breaking change which adds functionality)

Checklist:

• [x] My code has been run through clang-format.
• [x] I have read the contributing document.
• [x] My code is not on the master branch.
• [x] The code has been tested.
• [x] All commit messages are properly formatted and commits squashed where appropriate.
• [x] I have included updates to all appropriate documentation.

[Warchamp7]

The additional hotkey option was my proposal in lieu of a checkbox so I'm fine with this on the UX front.

[derrod]

Fixed up a rebase whoopsie that broke the build. Should be g2g now.