Replace v0.6 scene tests (valid and invalid); reorganise and expand transform tests

[clbarnes]

• I've gotten rid of the existing scene tests because they were more "real usage" focused rather than "minimal reproducible example"
• The previous transform tests were based on multiscales. Scenes allow a much simpler listing of coordinate systems and transforms (especially for the validate_zarr tests) so I've used those instead.
• I now have valid tests covering all transforms. All of the non-MUST transforms are under their own profile - i.e. a directory alongside core and strict. That way they're easy to skip.
• I think I've got the displacements and coordinates transforms right, but honestly who knows...
• where most of the cases which require arrays (i.e. multiscales) those arrays are left blank; for the transforms (path-form affines and rotations, coordinates, displacements) I've filled them in because they're very small and level 4 validation requires validating the contents of those arrays
• in these test cases, the simplest form of most transforms are used (e.g. rotations like [[1, 0], [0, 1]]). Exercising more complicated forms should be left to the transform_coordinates kind of test

TODO

• valid
  • scene
  • transforms
• invalid
  • scene
  • transforms