feat: file upload

[matheins]

Describe the feature you'd like to request

Add a field type wich allows the user to upload one or multiple files. The forms creator needs a way to see the submitted files. Upload should be limited to specific file types (images, docs, pdfs) and a max upload size (5mb).

Describe the solution you'd like to see

A new field type that displays a file picker.
The creator sees the files as a url in the submission table.

Additional information

No response