[discuss] form.field.Select => form.field.Combobox refactoring

@ExtAnimal @mxmrtns

Max would like to see a SelectField implementation which is based on select and option tags.

Imho a ComboBox can already handle the functionality (via editable: false) and a real SelectField would add all options directly into the DOM. However, I am open minded :)

If you decide that the separation makes sense, we will need to rename the current form.field.Select into form.field.ComboBox (scope of this ticket) and then create a follow up ticket to create a new form.field.Select. The new implementation should be pretty easy.

In case you decide to just stick to the current implementation, this ticket can also get closed.