Increase type coverage of WHILE_LOOP

WHILE_LOOP updated:
* now supports INT8, INT16, FP32, FP16, BF16 and INT32
* use data generation library where types are supported
* reduce tensor size as loop body ops have own tests

Add broadcast mode to FIXED_DATA generation mode to allow
setting tensor to single value

Change-Id: I243474e125fafc0f97a01dac2a2ccb445224e268
Signed-off-by: Jeremy Johnson <jeremy.johnson@arm.com>