Make a napari frontend prototype

[niksirbi]

napari has multiple built-in layer types which could be useful for movement.

• The Image layer could be used to display video frames
• The Points layer can be used to represent keypoints, see this example
• The Tracks layer can be used to visualise keypoint trajectories across time
• The Vectors layer can be used to show stuff like head orientation
• The Shapes layer can be used to create and show ROIs

Napari widgets can be created easily.

I will first make a prototype with the following features:

### Tasks
- [ ] https://github.com/neuroinformatics-unit/movement/issues/38
- [ ] https://github.com/neuroinformatics-unit/movement/issues/48
- [ ] https://github.com/neuroinformatics-unit/movement/issues/47
- [ ] https://github.com/neuroinformatics-unit/movement/issues/49
- [ ] https://github.com/neuroinformatics-unit/movement/issues/4
- [ ] https://github.com/neuroinformatics-unit/movement/issues/50