apps: Share common source between applications

Multiple source files in the src/apps/cam/ directory are used by cam,
qcam and lc-compliance. They are compiled separately for each
application. Move them to a new src/apps/common/ directory and compile
them in a static library to decrease the number of compilation
operations.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Umang Jain <umang.jain@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

src/apps/lc-compliance/main.cpp

@@ -14,8 +14,9 @@
 
 #include <libcamera/libcamera.h>
 
+#include "../common/options.h"
+
 #include "environment.h"
-#include "../cam/options.h"
 
 using namespace libcamera;