Fixed/improve argument handling for enable-extension/disable-extension.
Review Request #11069 — Created July 5, 2020 and submitted
weren't properly handling the extension ID provided on the command line,
causing both commands to error out.
This change fixes these to reference the option where the ID is stored,
fixing both commands.
It also improves both, allowing multiple extensions to be enabled or
disabled at a time.
Tested both commands with multiple IDs.