refactor(cts): Reduce tosa_verif_build_tests py file sizes

Reduce the files sizes of tosa_test_gen.py and tosa_arg_gen.py by
moving classes into their own files.

Moved OutputShaper to tosa_output_shaper.py from tosa_test_gen.py
Moved build_* functions to new TosaBuildGen class in tosa_build_gen.py
 from tosa_test_gen.py
Moved TosaTensorGen to tosa_tensor_gen.py from tosa_arg_gen.py
Moved TosaQuantGen to tosa_quant_gen.py from tosa_arg_gen.py
Moved TosaTensorValuesGen to tosa_tensor_values_gen.py from
 tosa_arg_gen.py

Signed-off-by: Jeremy Johnson <jeremy.johnson@arm.com>
Change-Id: I5c2179905a12acc101ba862f1ea368ac25f259f7