Consider making this lib ui library independent

[anbraten]

A idea that came to my mind recently (especially looking at some issues with formkit) is to make this library Independent from the ui component library.

Idea:

• this library has no form element components by default (remove formkit)
• it provides a schema renderer for forms. Elements can
  • emit changes, receive values
  • receive props from schema
  • have children / slot
  • have validation rules
  • be hidden by some validation expression
• it provides a form builder: only providing the drag and drop, options panel, new element panel elements (no actual form element like textfield, those will be injected)