repl: filter integer keys from repl tab complete list

Refactored version of https://github.com/joyent/node/pull/25819

Removes integer keys (and keys starting with numbers) from
candidate list on repl tab complete. Refactored the originally
submitted change to simplify and ensure that the integer keys
do not show up on objects either.

Reviewed By: Sakthipriyan Vairamani <thechargingvolcano@gmail.com>
PR-URL: https://github.com/nodejs/node/pull/2409