Experiment: Merge move gizmos

Today we have two distinct gizmos for moving an item:

- The free move tool: click on the item to drag it along the ground
- The move tool: click on the gizmo’s arrows or planes to move in a single direction or plane

This distinction is confusing, and it’s clunky to switch between each. The free move tool’s gizmo is also too subtle and can be missed. It’s also inefficient that by default all items start out with the free move tool. We could pack both into one:

- Click on the item to drag it along the ground
- Click on the gizmo’s arrows or planes to move in a single direction or plane


We can toggle between snap to grid and free movement. We should make the grid-based movement the default setting.