Redesign fs_dev, raw_dev, introducing device_partition and switch_fs.

In theory, one could mount an encrypted FAT partition itself coming from a disk image, etc.

fusee/fusee-secondary/src/raw_dev.h

@@ -0,0 +1,16 @@
+#ifndef FUSEE_RAW_DEV_H
+#define FUSEE_RAW_DEV_H
+
+#include <stddef.h>
+#include <stdint.h>
+#include <stdbool.h>
+#include "device_partition.h"
+
+#define RAWDEV_MAX_DEVICES 16
+
+int rawdev_mount_device(const char *name, const device_partition_t *device, bool mount_immediately);
+
+int rawdev_unmount_device(const char *name);
+int rawdev_unmount_all(void);
+
+#endif