API updates and other transitions for 1.2.0

[A248]

API:

• [ ] Deprecate the existing seekAfter/seekBefore APIs, and add a new seek method which works similarly to pagination anchors.

Configuration:

• [ ] Switch to MiniMessage (#208)
• [ ] Use YAML new lines instead of lists for punishment messages
• [ ] Ability to change the punishment message for each layout track
• [ ] Remove usage of %PREVIOUSPAGE%, the legacy pagination variable. Update automatically to %LASTPAGE%
• [ ] Multi-language support, if enabled, by loading all languages from folder (#312)
• [ ] Addon configuration is merged into main file (#222)
• [ ] Configure listener priority (see below)

Platform-related:

• [ ] Switch Velocity connection listener to PostOrder.HIGH by default, but make configurable. Use the legacy value of PostOrder.EARLY for migration purposes.
• [ ] Make all platforms have their own configuration interface, similarly to addons. Unlike addons, these interfaces can be located in bans-core.