Enable sync confirmations from the command-line

[OpenBagTwo]

GIVEN Alex is using EnderChest to sync her Minecraft setups AND while she generally wants to use the standard 5-second confirmation time, this one time she wants to explicitly provide confirmation before carrying out the sync

WHEN she runs the command:

enderchest open --wait prompt

THEN EnderChest will perform a dry run of the open operation, report the high-level summary and then ask for explicit confirmation before proceeding

SO that, in order to enable this behavior, Alex doesn't have to edit her enderchest.cfg file only to revert the change afterwards

Notes

• This applies for both open and close
• "confirm" should also be accepted, both here and in the enderchest.cfg file
• I'm also in favor of adding an explicit --confirm flag

[OpenBagTwo]

I'm dropping the idea for a --wait prompt option in favor of an unambiguous --confirm, because implementing my own "is this an int?" parsing is simply not worth it, especially when argparse's int-handling is so darn snazzy:

$ enderchest close -w seven
usage: enderchest close [-h] [--root ROOT_FLAG] [--verbose] [--quiet] [--dry-run] [--exclude EXCLUDE [EXCLUDE ...]]
                        [--timeout TIMEOUT] [--wait SYNC_CONFIRM_WAIT]
                        [root]
enderchest close: error: argument --wait/-w: invalid int value: 'seven'