InputReader: Get Bluetooth address from InputDeviceIdentifier

The InputDevice class in Reader stores the InputDeviceIdentifier. When
the policy wants to get the Bluetooth address of an InputDevice, fetch
it from there.

Bug: 243005009
Test: atest inputflinger_tests
Change-Id: I5d881a11cb1bc318258faf1f498db1ca29ae8537
diff --git a/services/inputflinger/reader/include/InputDevice.h b/services/inputflinger/reader/include/InputDevice.h
index afb1bed..b9a2b4c 100644
--- a/services/inputflinger/reader/include/InputDevice.h
+++ b/services/inputflinger/reader/include/InputDevice.h
@@ -51,6 +51,9 @@
     inline int32_t getGeneration() const { return mGeneration; }
     inline const std::string getName() const { return mIdentifier.name; }
     inline const std::string getDescriptor() { return mIdentifier.descriptor; }
+    inline std::optional<std::string> getBluetoothAddress() const {
+        return mIdentifier.bluetoothAddress;
+    }
     inline ftl::Flags<InputDeviceClass> getClasses() const { return mClasses; }
     inline uint32_t getSources() const { return mSources; }
     inline bool hasEventHubDevices() const { return !mDevices.empty(); }