Introduce CL kernel cache feature

Introduce CL kernel cache feature

This patch introduces CL kernel cache feature for
NN runtimes such as ARMNN or other in-house versions.

Originally, this feature came from utils/Utils.cpp and utils/Utils.h
files but was used just for testing.

Caching CL kernel binaries is mandatory and required for real product
because inference performance at first run is one of very important
factors. This patch exposes two API - save_program_cache_to_file
and restore_program_cache_from_file so that NN runtimes can use
these API to cache the compiled CL kernel binaries.

Changelog v1.
- Reordered including headers suggested by Manuel Bottini.
- Updated description.
Changelog v2.
- Drop function descriptions.
Changelog v3.
- Fix build error with opencl = 0. As for this, it moves two functions,
  save_program_cache_to_file and restore_program_cache_from_file,
  to src/runtime/CL/Utils.cpp and arm_compute/runtime/CL/Utils.h,
  and set ARM_COMPUTE_CL flag only when opencl = 1.
  This change makes CL kernel cache feature to depend on OpenCL support.
Changelog v4.
- Fix coding_standard_checks error.
Changelog v5.
- Add a new cpp file to Android.bp to fix coding_standard_checks error.
Changelog v6.
- rebased on top of master, and dropped _new_built_programs_map object
  so it adds compiled CL kerne binaries per model to a given file.
Changelog v7.
- Correct descriptions.
- Correct arm_compute/runtime/CL/Utils.h file description.
- Correct src/runtime/CL/Utils.cpp file description.
- Drop ARM_COMPUTE_CL ifdef ~ endif from examples/cl_cache.cpp
- Do not add 'ARM_COMPUTE_CL' flag at SConscript.

Change-Id: I8c640fb1809ca79191daf5b1ff72a50dd492c36d
Signed-off-by: Inki Dae <inki.dae@samsung.com>
Reviewed-on: https://review.mlplatform.org/c/ml/ComputeLibrary/+/2914
Tested-by: Arm Jenkins <bsgcomp@arm.com>
Reviewed-by: Georgios Pinitas <georgios.pinitas@arm.com>
Comments-Addressed: Arm Jenkins <bsgcomp@arm.com>