Improve files field#232

1. Avoid first dialog in files field

With Kirby 3.5 the files field behaviour changed that you always have click twice to select a a file, this slows down the workflow. It could be avoided if the “select” and “upload” buttons would be placed directly above the field instead of the “add” button. There should be enough space for this two buttons.

2. Extend link options in Blueprint

Also it would it would be nice to have an extra option on the behaviour what happens when click on an selected file. Now it either opens the file or you can disable the link. But it would be nice to have an third option that opens the dialog to change the file. It could look like this in the Blueprint:

mainimage:
  label: Image
  type: files
  query: page.images
  multiple: false
  link: modal