Add minimum duel amount setting to the duel module

[pajlada]

Pull request checklist:

• CHANGELOG.md was updated, if applicable
• Documentation in docs/ or install-docs/ was updated, if applicable
• I have tested all changes

Changes:

• typing: get_duel_stats return bool
• typing: pajbot.utils - define __all__ for explicit exports
• typing: pajbot.managers.websocket typing for emit function
• format: move each attribute to its own line for show_on_clr
• Add minimum point amount to the duel module

I have decided not to change anything with the output, it's still hardcoded as whispers for error messages.
If we want to change this, it should be a new feature request.

Fixes #2400

[pajlada]

Looks good to me!