cli: add FaultError to default imports

It's not uncommon to need to catch FaultError in the CLI. Josef Bacik
complained that he often forgets to import it when he needs it, so let's
do it by default.

Signed-off-by: Omar Sandoval <osandov@osandov.com>

drgn/cli.py

@@ -345,6 +345,7 @@ def run_interactive(
         "__doc__": None,
     }
     drgn_globals = [
+        "FaultError",
         "NULL",
         "Object",
         "cast",