Provide a gap between the Note Velocity/Pan toggling and the Volume/Pan bars in Volume/Pan editor of Piano Roll

### Enhancement Summary
Adding a note at the the very beginning causes the note's Volume/Pan bar to be half hidden by the Volume/Pan toggling, and frequently causes switching from Volume to Pan or vice versa when one tries to edit said quality of the very first note/ the leftmost note of the visible section of the piano roll



https://user-images.githubusercontent.com/103920743/170061308-2b45ad29-fa63-437b-8f3e-96b0c3f528a3.mp4

Possible solutions are:
1) Providing a gap between the bars and the switch, which would involve separating all of the notes from the keyboard on the left by a small margin
2) Reducing the size of the switch from the entire rectangle to the left on the notes to a small area.

#### Justification
This isn't a major problem, and can be easily worked around by being careful/moving note to the right to change volume/scrolling to an appropriate position (this one doesn't work if it's the first note, in the very beginning of the first bar), but it is quite an avoidable issue, and modifying it would provide a more seamless experience to users.
The improvement in experience and preventing such minor annoyances, to people new to LMMS and unused to the quirk at any rate, I believe would be worth the change.

#### Mockup

Possible option? But there are any number of ways to solve this.

Start in the Piano Roll's Volume/Pan editor and reproduce the overlap between the Note Velocity/Pan toggle and the leftmost Volume/Pan bar. Compare the proposed gap or smaller toggle area, then verify that the first visible note can be edited without accidentally switching between Volume and Pan.

Written by the indexing model from the issue text.