Add File input element

A file input element allow the user to select a file from his computer to upload it, for instance when creating/updating a row.

Some constraints:

• The file input should be configurable to only accept certain file type
• (v2) it can display the preview of an image if it's one (or even an icon for other types)
• We should have a way to see upload progress while we submit the action somehow. It can't be on the file input itself but when the action that upload the file is happening.
• It would be great to have a way to specify the "current value" when it exists.
• It should support multiple file selection
• Supports drag&drop file