Support mangling and demangling independently of programs

[eyalroz]

CUDA NVRTC programs have the API function:

nvrtcResult nvrtcGetLoweredName(
    nvrtcProgram prog,
    const char *const name_expression,
    const char** lowered_name);

which mangle a function's name (or its signature). Unfortunately:

• This requires a program, although mangling should in in principle be uniform over all programs - independent of the NVRTC program.
• No demangling :-(

We should try and offer a program-independent mangling and de-mangling functionality which covers everything CUDA does with mangled names (which is probably not just plain vanilla Itanium ABI).