Widgets for text-input based on ratatui.

Eventhandling is currently crossterm only.

In practice event-handling is calling 1 or 2 functions on the state, so this
should be simple to map for other systems. 

TextInput

Basic text input field.

• Text selection with keyboard + mouse
• Possible states as styles: Focused, Invalid

#MaskedInput

Text input with an input mask.

• Text selection with keyboard + mouse
• Possible states as styles: Focused, Invalid
• Pattern based input -> "##,###,##0.00"
  • number patterns: 09#-+.,
  • numeric text: HhOoDd
  • text: lac_
  • arbitrary separators between sub-fields
• info-overlay for sub-fields without value
• Localization with [rat-input::NumberSymbols]

#Button