[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/examples/RomiReference/commands/drivetime.py

@@ -0,0 +1,46 @@
+#
+# 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 commands2
+import wpilib
+
+from subsystems.drivetrain import Drivetrain
+
+
+class DriveTime(commands2.Command):
+    """Creates a new DriveTime. This command will drive your robot for a desired velocity and time."""
+
+    def __init__(self, velocity: float, time: float, drive: Drivetrain) -> None:
+        """Creates a new DriveTime. This command will drive your robot for a desired velocity and time.
+
+        :param velocity: The velocity which the robot will drive. Negative is in reverse.
+        :param time:  How much time to drive in seconds
+        :param drive: The drivetrain subsystem on which this command will run
+        """
+
+        self.velocity = velocity
+        self.duration = time
+        self.drive = drive
+        self.addRequirements(drive)
+
+        self.startTime = 0.0
+
+    def initialize(self) -> None:
+        """Called when the command is initially scheduled."""
+        self.startTime = wpilib.Timer.getTimestamp()
+        self.drive.arcadeDrive(0, 0)
+
+    def execute(self) -> None:
+        """Called every time the scheduler runs while the command is scheduled."""
+        self.drive.arcadeDrive(self.velocity, 0)
+
+    def end(self, interrupted: bool) -> None:
+        """Called once the command ends or is interrupted."""
+        self.drive.arcadeDrive(0, 0)
+
+    def isFinished(self) -> bool:
+        """Returns true when the command should end"""
+        return wpilib.Timer.getTimestamp() - self.startTime >= self.duration