scylla-gdb.py: scylla_ptr: move actual logic into analyze()
scylla-gdb.py: scylla_ptr: move actual logic into analyze()

In preparation to this method being made usable for outside code.

scylladb/scylla,scylladb/scylla,avikivity/scylla,avikivity/scylla,scylladb/scylla,scylladb/scylla,avikivity/scylla