Remove automatic formatting of integer values

[phyr97]

This PR removes the formatting for a value of a number field. This should lead to the behavior that formatting is optional and is not carried out by default.

Formatting of the number field must now be defined with the render option on the field itself. If number fields have benefited from the previous standard formatting, the following render function can now be used as an example:

render: fn assigns ->
  ~H"""
  <p><%= Number.Delimit.number_to_delimited(@value, precision: 0, delimiter: ".") %></p>
  """
end

[Flo0807]

I changed the title of this PR because the term "number field" can be misleading, as formatting was performed for all Backpex fields.