Introduce `FakeResetDriverWatchdog` to simulate driver reset triggers.
Update existing tests and add a new test, `test_notify_reset_driver`, to
verify reset notifications using the event signaling mechanism.
Introduces test infrastructure and mockup classes for
`dbus_middleware1`. Includes `BusProvider` test setup, fake device
implementations, and initialization logic to support session bus
testing. Enhances testability and isolation of the D-Bus middleware
components.
