Bulldozer in Piano roll

[allejok96]

New edit mode to quickly scale and move things around. Stems from #6140. Forgive the bad English.

https://user-images.githubusercontent.com/7693838/185953603-090a0912-c46c-435d-8c69-5c351ccd4ed4.mp4

Didn't want to wait for piano roll rewrite any more. Needed this feature.

New stuff

• Scrollable edit mode button in the toolbar
• Edit mode button and note actions button remembers last used
• Bulldozer move:
  • Selects all notes to the right if no notes are selected
  • Stretches the notes that touches or overlaps the left side
• Bulldozer resize:
  • Proportional, like shift-resize
  • All notes are proportionally resized between the red lines (the edges of the selection)
  • Moved note snaps to grid
  • Notes in between are not quantized - proportions kept intact (applies to ordinary shift-resize too)
  • Moves posterior notes
• Hold shift to temporarily disable bulldozer and move or resize a single note

Bugs fixed

• Disable quantization when moving notes in grid snap mode by holding alt
• Resize in grid snap mode snaps to closest line correctly
• Length of new note after resizing is taken from the last clicked note, not the rightmost note
• Knife mode always exits to draw mode when right clicking (not a bug)

Needs testing

• Drawing
• Moving / resizing
• Modifiers
• Hitting the top/bottom
• Hitting other notes in bulldozer mode
• Switching between modes (knife mode in particular)
• Messing with drum notes
• Minimum note lengths when resizing
• Grid snapping vs nudge

Beware of bugs

I know there's a ton in the old code. I didn't want to fix them to keep the PR clean, but some of them just had to go. Hope I didn't introduce that many new though.

[allejok96]

Made it draft since dragNotes needs some more work with note boundaries etc