feat: extend video recording by Record Selection

[lenisko]

Not sure if that's possible, but it would be very convenient to have similar abilities for video recording as we have for screenshots.

Since recording a selected app and whole screen is there, what's missing is the selection.

[castdrian]

This is probably possible, I think screencapturekit accepts passing a custom rect, however it would require cloning the behavior of the native screenshot app, drawing an invisible window and then allowing the drawing of rectangles

[philocalyst]

You might have already seen this @castdrian, but this project is focused on extending the screen recording functionality in exactly the same way (https://github.com/lihaoyun6/QuickRecorder). Also written in swift, so maybe you could just integrate the features that make sense directly?