[hal] Add CAN Bus Map (#8765)

We will want a better API for higher level devices that expect to be on
motioncore, but for ones that are not expected to be, it'll be really
nice to have an API that can let us map the motioncore can bus to its
HAL index.

hal/src/main/native/include/wpi/hal/CANBusMap.h

@@ -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>
+
+#include "wpi/hal/Types.h"
+
+/**
+ * @defgroup hal_canapi CAN BUS Mapping Enums
+ * @ingroup hal_capi
+ * @{
+ */
+
+HAL_ENUM(HAL_CANBusMap) {
+  HAL_CAN_BUS_S0 = 0,
+  HAL_CAN_BUS_S1 = 1,
+  HAL_CAN_BUS_S2 = 2,
+  HAL_CAN_BUS_S3 = 3,
+  HAL_CAN_BUS_S4 = 4,
+  HAL_CAN_BUS_D0 = 5,
+  HAL_CAN_BUS_D1 = 6,
+  HAL_CAN_BUS_D2 = 7,
+  HAL_CAN_BUS_D3 = 8,
+  HAL_CAN_BUS_D4 = 9,
+  HAL_CAN_BUS_D5 = 10,
+  HAL_CAN_BUS_D6 = 11,
+  HAL_CAN_BUS_D7 = 12,
+  HAL_CAN_BUS_D8 = 13,
+  HAL_CAN_BUS_D9 = 14,
+  HAL_CAN_BUS_D10 = 15,
+  HAL_CAN_BUS_D11 = 16,
+  HAL_CAN_BUS_D12 = 17,
+  HAL_CAN_BUS_D13 = 18,
+  HAL_CAN_BUS_D14 = 19,
+  HAL_CAN_BUS_D15 = 20,
+  HAL_CAN_BUS_D16 = 21,
+  HAL_CAN_BUS_D17 = 22,
+  HAL_CAN_BUS_D18 = 23,
+  HAL_CAN_BUS_D19 = 24,
+};
+
+/** @} */