Usability improvements for the Web Client

The following usability improvements for the Web Client have been made.

Keyboard interaction for hierarchical lists improved (#668818)

The hierarchical list component in the Web Client has been optimized for more reliable keyboard interaction. The cursor no longer jumps after selecting a suggested value, so that the user can type additional characters. In addition, the dropdown popup no longer disappears after value selection, and support for German special characters and umlauts has been restored.

Automatic refresh of modified cases (#669262)

The Web Client now detects when a case that is currently open in the browser has been modified by another user or another process, e.g. an incoming email.

If the case is in view mode, the case is reloaded automatically so the user immediately sees the updated data. A green notification bar is shown to inform the user about the reload.

If the case is in edit mode, a yellow notification bar is displayed, informing the user about the changes.