Update long screenshot crop per mocks

- Can crop on both axes (for alignment with markup)
- Updated handle drawing
- Vertical dragging is functionally the same, but horizontal dragging is
allowed if vertical hasn't triggered (intentionally giving priority to
vertical since that's the important function here).
- Lots of refactoring in CropView to allow for this without filling it
with switch statements.
- Only showing magnifier for vertical cropping (for now).
- Scrim the long screenshot image but nothing beyond that.
- Lessen scrim opacity

Bug: 180967468
Test: Manual testing
Change-Id: I85593414ab5aca12b365da34529d2033226b1cfb