sim-se: Add special paths for MPI, libnuma, ROCm support

sim-se: Add special paths for MPI, libnuma, ROCm support

Add new pseudo files which are read by various runtime libraries
including MPI, libnuma, and ROCm. New paths include /proc/self/maps,
/dev/urandom, and /sys/devices/system/cpu/online.

Change-Id: I00a82788cff9d6f4f16fc56230b18be9b76c4015
Signed-off-by: Brandon Potter <Brandon.Potter@amd.com>
Signed-off-by: Michael LeBeane <Michael.Lebeane@amd.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/25367
Tested-by: Gem5 Cloud Project GCB service account <345032938727@cloudbuild.gserviceaccount.com>
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>