Add method to get id of virtual camera

Also, add CtsVirtualDevicesCameraTestCases to virtualcamera
service postsubmit.

Test: atest CtsVirtualDevicesCameraTestCases
Bug: 310857519
Change-Id: I9f2e070a49bbf94694e996e4793a7997fbcb7b9e
diff --git a/services/camera/virtualcamera/VirtualCameraDevice.h b/services/camera/virtualcamera/VirtualCameraDevice.h
index 0c95b7a..97d6122 100644
--- a/services/camera/virtualcamera/VirtualCameraDevice.h
+++ b/services/camera/virtualcamera/VirtualCameraDevice.h
@@ -87,6 +87,8 @@
   // "device@{major}.{minor}/virtual/{numerical_id}"
   std::string getCameraName() const;
 
+  uint32_t getCameraId() const { return mCameraId; }
+
  private:
   const uint32_t mCameraId;
   const std::shared_ptr<