libcamera/base: Move span to base library

Move span, and adjust the Doxygen exclusion as well.

Reviewed-by: Paul Elder <paul.elder@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

test/utils.cpp

@@ -11,11 +11,11 @@
 #include <string>
 #include <vector>
 
-#include <libcamera/geometry.h>
-#include <libcamera/span.h>
-
+#include <libcamera/base/span.h>
 #include <libcamera/base/utils.h>
 
+#include <libcamera/geometry.h>
+
 #include "test.h"
 
 using namespace std;