[hal,wpilib] Switch CANBusMap to Enum, use it for CAN API (#8977)

Will make it easier to solve
https://github.com/wpilibsuite/SystemcoreTesting/issues/286

wpilibc/src/main/native/include/wpi/hardware/bus/CANBusMap.hpp

@@ -0,0 +1,66 @@
+// 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
+
+namespace wpi {
+
+/**
+ * CAN bus mapping.
+ *
+ * S0-S4 are Systemcore CAN buses. D0-D19 are Motioncore CAN buses.
+ */
+enum class CANBusMap {
+  /// CAN bus S0.
+  CAN_S0 = 0,
+  /// CAN bus S1.
+  CAN_S1 = 1,
+  /// CAN bus S2.
+  CAN_S2 = 2,
+  /// CAN bus S3.
+  CAN_S3 = 3,
+  /// CAN bus S4.
+  CAN_S4 = 4,
+  /// CAN bus D0.
+  CAN_D0 = 5,
+  /// CAN bus D1.
+  CAN_D1 = 6,
+  /// CAN bus D2.
+  CAN_D2 = 7,
+  /// CAN bus D3.
+  CAN_D3 = 8,
+  /// CAN bus D4.
+  CAN_D4 = 9,
+  /// CAN bus D5.
+  CAN_D5 = 10,
+  /// CAN bus D6.
+  CAN_D6 = 11,
+  /// CAN bus D7.
+  CAN_D7 = 12,
+  /// CAN bus D8.
+  CAN_D8 = 13,
+  /// CAN bus D9.
+  CAN_D9 = 14,
+  /// CAN bus D10.
+  CAN_D10 = 15,
+  /// CAN bus D11.
+  CAN_D11 = 16,
+  /// CAN bus D12.
+  CAN_D12 = 17,
+  /// CAN bus D13.
+  CAN_D13 = 18,
+  /// CAN bus D14.
+  CAN_D14 = 19,
+  /// CAN bus D15.
+  CAN_D15 = 20,
+  /// CAN bus D16.
+  CAN_D16 = 21,
+  /// CAN bus D17.
+  CAN_D17 = 22,
+  /// CAN bus D18.
+  CAN_D18 = 23,
+  /// CAN bus D19.
+  CAN_D19 = 24,
+};
+}  // namespace wpi