TOSA 0.50.0 release tag

- Add a new definition for TOSA levels. Levels define operator parameter
  ranges that an implementation shall support. This is distinct from a profile
  that defines the operations and data-types supported
- Tensor coordinates are clarified to be 32-bit integer values
- Operator clarifications: SLICE, RESIZE, RESCALE
- Add the ability to CAST between floating-point types

See the git log for all changes.