Add functionality to "warm-up" recorder, to avoid stall on first recording.

[supermoos]

As per discord discussion there's a stutter / lag happening at the beginning of the first recording. The suggested workaround from discord thread is: "The workaround is pretty simple: create a recorder, commit exactly one video frame (empty array), then finish recording and delete the file.
Best done in a loading screen" - would be nice to have some helper function that could be called that does this.

[olokobayusuf]

@supermoos we've added this as a toggle in VideoKitRecorder. It's called prepareOnAwake and will run this preparation when the component awakes (on scene load, or when you instantiate the component from code). This will be in the next update.

[olokobayusuf]

Implemented in VideoKit 0.0.10