Refer to doc/xip.md for details.
Add shorthand "--xip" option for wamrc, which is equal to "--enalbe-indirect-mode --disable-llvm-intrinsics"
Auto detect whether file is XIP file before loading module in posix like and linux-sgx platforms, and if yes, mmap executable memory automatically to run the XIP file. Add document about XIP feature. Enable test spec cases with XIP feature.