Cinnamon Settings: Add settings module identifier to interface

[timfeierabend]

Currently, when you enter a setting module from Cinnamon Settings, the title bar always says "System Settings" - no matter which setting you're in. The settings module doesn't have an indicator which setting you're in either.

This behavior is different from when you enter the setting directly via a .desktop file or cinnamon-settings module from the terminal where the window's title is the settings module.

Proposed idea: Add a breadcrumb to the window title bar whenever you enter a module.