Fix lazy data gen mode for CTS

Enable lazy_data_gen mode support for all CTS tests in
tosa_verif_conformance_generator

Add support for reading SHAPEs of [0] in ref model.

Change datagenerator to use serialization_lib save_npy to
write out data files in correct format.
Fix SHAPE to be output as int64 numpy format.

Clean up unused data generator functions in tosa_verif_build_tests

Add datagenerator tests for numpy format output.
Merge test_datagenerator.py tests into test_tosa_datagenerator.py

Disable cond_if_const test generation is lazy_data_gen is
requested as the work-around for loading const data late does not
work with these tests - some proper functionality to support lazy
data gen is needed.

Signed-off-by: Jeremy Johnson <jeremy.johnson@arm.com>
Change-Id: I9e18c960fbd636463ddf9e0bc2bf6f2ac9a760f5