[robotpy][examples] Split examples and snippets (#8944)

This also updates the bazel scripts to behave more like the C++ and Java
examples, and updates the copybara scripts to be able to sync up
`mostrobotpy`

robotpyExamples/snippets/DutyCycleInput/robot.py

@@ -0,0 +1,27 @@
+#!/usr/bin/env python3
+#
+# Copyright (c) FIRST and other WPILib contributors.
+# Open Source Software; you can modify and/or share it under the terms of
+# the WPILib BSD license file in the root directory of this project.
+#
+
+import wpilib
+
+
+class MyRobot(wpilib.TimedRobot):
+    def __init__(self):
+        """Robot initialization function"""
+        super().__init__()
+
+        self.dutyCycle = wpilib.DutyCycle(0)
+
+    def robotPeriodic(self):
+        # Duty Cycle Frequency in Hz
+        frequency = self.dutyCycle.getFrequency()
+
+        # Output of duty cycle, ranging from 0 to 1
+        # 1 is fully on, 0 is fully off
+        output = self.dutyCycle.getOutput()
+
+        wpilib.SmartDashboard.putNumber("Frequency", frequency)
+        wpilib.SmartDashboard.putNumber("Duty Cycle", output)