Arm backend: Add unit test for DeiT-Tiny model on TOSA-MI backend (#10391)

Add unit test that runs the DeiT-Tiny model on the TOSA-MI profile. The
output performance is not great at the moment. An internal ticket has
been created to debug this problem later.

### Test plan
Command used to test the patch:
`python -m pytest -s -c /dev/null --log-level=DEBUG
"backends/arm/test/models/test_deit_tiny_arm.py"`


Co-authored-by: Martin Lindström <Martin.Lindstroem@arm.com>