frontend/jupyter: run all cells above/below dropdown button in cell toolbar

[haraldschilly]

Description

• this adds a small dropdown to get quick access for running all cells above or below
• I'm also changing the icons, because they are not telling much, or even point in the wrong direction
• this also adds support for rotated menu icons

Checklist:

• [ ] Testing instructions are provided, if not obvious
• [ ] Release instructions are provided, if not obvious

[williamstein]

When does it include the current cell? The naming strongly suggests it never includes the current cell.

[williamstein]

[williamstein]