Create `boardgame-util config init`

[jkomoros]

Set reasonable defaults, basically copying over config.SAMPLE.json (it has a lot of good defaults)

Update tutorial.md

[jkomoros]

Useful for #662

• [x] Implement config init
• [ ] Add --override-config top-level option
• [x] Have sample, default, and minimal (default is obviously default). These same values can be passed as global options as override confis, for first run
• [x] Test output of all three starter things
• [x] config set shouldn't operate on a blank config unless --force is passed
• [x] tutorial.md should mention using config init
• [x] Config init should allow specifying lcoation on command line via --config

[jkomoros]

Fixed by 383d18d