Passing raw binary cpt to initiate memory

[shinezyy]

Usage:

• For a gz cpt: --generic-rv-cpt=cpt.gz
• For a raw binary cpt: --generic-rv-cpt=cpt.bin --raw-cpt

About raw binary cpt:

• We only allow to mmap to the cpt.bin to accelorate init stage
• We bypass the imageData of GEM5 in a dirty way, because it initiate the physical memory with the pmem proxy which runs slowly and always (unnecessarily) write to zero pages to break COW

Other changes:

• Fix the parameter type of ImageData Read/Write/Clear: using size_t instead of int to allow objects larger than 4GB