DEV: gdb: add a new utility to extract libs from a core dump: libs-from-core

DEV: gdb: add a new utility to extract libs from a core dump: libs-from-core

This utility takes in argument the path to a core dump, and it looks
for the archive signature of libraries embedded with "set-dumpable libs",
and either emits the offset and size of stdout, or directly dumps the
contents so that the tar file can be extracted directly by piping the
output to tar xf.