Refs #21327; Refactoring the Character Limit Form:

- Introduced getSetting, setValues and removeValues in order to avoid
  logic repetition
- Saved the form inputs in order to dinamically set and retrieve the
  form values instead of hardcoding the values
- Take into consideration the readability checkbox
- Modified the json output in order for the field options to be saved
  on the field name instead of having the fieldname within the same
  list with it's options
- Focused the content type enabled in order to avoid empty inputs
  for options that had inputs