MLBEDSW-10723: MLCE: Add support for the Log operator in Regor

- Implemented Log operator with the generic LUT implementation
- Update SUPPORTED_OPS.md and vela.py to include the LOG operator
- In tflite_graph_optimiser.cpp:
  - Change the variable type of `prevLutResult` from float to int16_t.
  - Clamp the intermediate LUT value and explicitly cast it to int16_t,
    fixing precision and conversion issues in the LUT generation.

Change-Id: I8c877cb4f3c3c2da2eb82369fdd0269e938c4fe5
Signed-off-by: Johan Alfvén <johan.alfven@arm.com>