[lld-macho] Implement -dependency_info (partially - more opcodes needed)
The flag is not well documented, so this implementation is based on observed behaviour.
When specified, -dependency_info <path> produced a text file containing information pertaining to the current linkage, such as input files, output file, linker version, etc.
This file's layout is also not documented, but it seems to be a series of null ('\0') terminated strings in the form <op code><path>
<op code> could be:
`0x00` : linker version `0x10` : input `0x11` : files not found(??) `0x40` : output
<path> : is the file path, except for the linker-version case.
(??) This part is a bit unclear. I think it means all the files the linker attempted to look at, but could not find.
Differential Revision: https://reviews.llvm.org/D98559