Update `set` and add `list-modes` adb shell game commands

Hide `--mode` option from `set` command to default to use `custom`
mode. Rename `list` command to `list-configs` and add it to the game
commands' help message.

Bug: 243448953
Test: manual test
Change-Id: I4adae903ce48ba8aeb5e5b00154bec1953df9a9a