Show rename form in a modal window or a sidebar

Problem/Motivation

It's sometimes not so convenient to go to another page to rename a file. E.g. sometimes form data in other fields can be lost after this.

Steps to reproduce

N/A

Proposed resolution

Make possible to rename files "on fly" directly on the page where the file widget is located. So the rename form can appear in a modal window or maybe in a sidebar. The file widget's state has to be refreshed using AJAX after form is submitted.

Remaining tasks

TBD.

User interface changes

TBD.

API changes

TBD

Data model changes

N/A