Add ability to loop MIDI clips

[Itreza2]

May close #7907
Add the ability to create a "loop" behind a MIDI clip, as you can see on the following video :

2026-02-09.19-05-23.mp4

How to test :

• Open the contextual menu of any clip of an instrument track in the song editor
• Click on the new "Loop" option

If the case that this PR is validated, it should be easy to make Automation and Sample clips loop-able as well !

[sakertooth]

I was confused until I realized you have to set up your recording properly to show the context menus. I forgot how to do that in OBS (if you are using that).

[WeakOstra]

I am confused, how do you create the loop in the video? do you press any buttons? I can´t see clearly in the video.

[Itreza2]

I am confused, how do you create the loop in the video? do you press any buttons? I can´t see clearly in the video.

The loop is create by right-clicking the clip to open the contextual menu, and then selecting the "loop" option.
As sakertooth mentioned above, obs don't capture the context menus by default and I did not paid attention when recording.

[messmerd]

I really like this idea! It's simple but very handy. Kind of like ad-hoc patterns for ordinary clips. Maybe a better name would be "linked clips"?

It'd be great if you added support for automation clips and sample clips as well.