[boschshc] Support obtaining battery states (#13461) (#13631)

[boschshc] Support obtaining battery states (#13461) (#13631)

This change adds support for obtaining the battery state for the
following devices:

* Motion Detector
* Thermostat
* Twinguard
* Wall Thermostat
* Window/Door Contact

The following changes were made:

* Add system.battery-level and system.low-battery channels to Motion
Detector, Thermostat, Twinguard, Wall Thermostat and Window/Door Contact
* Add constant for battery-level and low-battery channels in
BoschSHCBindingConstants
* Implement abstract handler and service for battery-powered devices
* Let appropriate devices inherit the abstract implementation
* Add missing super calls in initializeServices() methods
* Rename existing getServiceURL() to getServiceStateURL() in HTTP client
* Add methods to retrieve service states without the suffix "/state" in
the URL
* Rename DeviceStatusUpdate to DeviceServiceData
* Let DeviceServiceData extend BoschSHCServiceState
* Extend DeviceServiceData DTO with model for faults
* Enhance bridge handler: handle updates without state sub-objects,
extract methods to enhance readability
* Add unit tests for all affected devices
* Minor code enhancements
* Update documentation

Signed-off-by: David Pace <dev@davidpace.de>