[hal, wpilib] Add OpMode support (#7744)

User code:
- OpModeRobot used as the robot base class
- LinearOpMode and PeriodicOpMode are provided opmode base classes
- In Java, annotations can be used to automatically register opmode classes

Additional user code functionality:
- OpMode (string) is available in addition to the overall
auto/teleop/test robot mode
- OpMode does not indicate enable (enable/disable is still separate)
- The HAL API uses integer UIDs; these are exposed at the user API level
as well for faster checks
- User code creates opmodes on startup (these have name, category,
description, etc).

DS:
- DS will present opmode selection lists for auto and teleop for
match/practice. During a match, the DS will automatically activate the
selected opmode in the corresponding match period.
- For testing, an overall mode is selected (e.g. teleop/auto/test) and a
single opmode is selected

Future work:
- Command framework support/integration
- Python annotation support
- Unit tests (needs race-free DS sim updates)
- Porting of examples

Co-authored-by: Joseph Eng <91924258+KangarooKoala@users.noreply.github.com>

wpilibc/src/main/native/include/wpi/opmode/OpMode.hpp

@@ -0,0 +1,45 @@
+// 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.
+
+#pragma once
+
+#include <stdint.h>
+
+namespace wpi {
+
+/**
+ * Top-level interface for opmode classes. Users should generally extend one of
+ * the abstract implementations of this interface (e.g. PeriodicOpMode or
+ * LinearOpMode) rather than directly implementing this interface.
+ */
+class OpMode {
+ public:
+  /**
+   * The object is destroyed when the opmode is no longer selected on the DS or
+   * after OpModeRun() returns.
+   */
+  virtual ~OpMode() = default;
+
+  /**
+   * This function is called periodically while the opmode is selected on the DS
+   * (robot is disabled). Code that should only run once when the opmode is
+   * selected should go in the opmode constructor.
+   */
+  virtual void DisabledPeriodic() {}
+
+  /**
+   * This function is called when the opmode starts (robot is enabled).
+   *
+   * @param opModeId opmode unique ID
+   */
+  virtual void OpModeRun(int64_t opModeId) = 0;
+
+  /**
+   * This function is called asynchronously when the robot is disabled, to
+   * request the opmode return from OpModeRun().
+   */
+  virtual void OpModeStop() = 0;
+};
+
+}  // namespace wpi