Implement scratchpad retrieving function

[shizzard]

The scratchpad retrieving function was implemented:
Interface:

const unsigned char *randomx_calculate_hash_scratchpad(
    randomx_vm *machine, 
    const void *input, 
    size_t inputSize, 
    const int randomxProgramCount
)

Differencies with randomx_calculate_hash_long_with_entropy_get_entropy:

• Keep in the intrinsics calls;
• Remove the final hash calculation step.

Differencies with randomx_calculate_hash:

• Remove the final hash calculation step;
• Make function interface simpler (no output pointer).