Always display input for widget title in widget edit mode.

[linuspahl]

Description

Motivation and Context

Before this change you could only change the widget name by double clicking on it. This is a bit inconsistent to similar cases in the UI and can be hard to understand. Now we always display an input for the title in the widget edit mode.

Fixes: https://github.com/Graylog2/graylog2-server/issues/7396