SensorReader PWM Refactor.

Refactored the pwm trigger and pwm detecter out of the year specific.

Change-Id: Ie89332fe6e1bcc0f465b742055ec4cf392a20c7e
diff --git a/y2019/BUILD b/y2019/BUILD
index 8705da0..7c987f6 100644
--- a/y2019/BUILD
+++ b/y2019/BUILD
@@ -46,6 +46,7 @@
         "//frc971/wpilib:logging_queue",
         "//frc971/wpilib:loop_output_handler",
         "//frc971/wpilib:pdp_fetcher",
+        "//frc971/wpilib:sensor_reader",
         "//frc971/wpilib:wpilib_interface",
         "//frc971/wpilib:wpilib_robot_base",
         "//third_party:wpilib",