Move camera.h to the frc971/ folder

The code for dealing with camera transformations is reasonably
year-generic, so move it into frc971/.

Change-Id: I7751ccd01c3e45093c8e548d65e0087b615f0ae0
diff --git a/y2019/control_loops/drivetrain/localizer_test.cc b/y2019/control_loops/drivetrain/localizer_test.cc
index 319065e..aa7f22f 100644
--- a/y2019/control_loops/drivetrain/localizer_test.cc
+++ b/y2019/control_loops/drivetrain/localizer_test.cc
@@ -30,6 +30,7 @@
                        kNumTargetsPerFrame, double>
     TestLocalizer;
 typedef typename TestLocalizer::Camera TestCamera;
+typedef typename TestLocalizer::Target Target;
 typedef typename TestCamera::Pose Pose;
 typedef typename TestCamera::LineSegment Obstacle;