Allows the Settings > Hotkeys screen to be localised, including hotkey decriptions, groups and contexts.
The hotkey names are exposed to localisation via KeycodeExts. Hotkey modifiers are similarly exposed via ModifersExts.
The Settings > Input screen has a Zoom Modifier dropdown, which shows the localised modifier name.
The --check-yaml utility command is taught to recognise all hotkey translation, so it can validate their usage.
* Add HotkeyDialogLogic.cs
* Add dialog-hotkey.yaml to all mods
* Add `GetFirstDuplicate` method to HotkeyManager to aid in validation
* Add "Player" and/or "Spectator" type to all hotkeys to allow for
validation based on overlapping types
* Change settings.yaml and SettingsLogic.cs to work with the new dialog
