utils: codegen: gen-controls.py: Move helper classes to separate file

The ControlEnum and Control helper classes defined in gen-controls.py
are useful for other generator scripts. Move them to a separate file to
make it possible to share them.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Daniel Scally <dan.scally@ideasonboard.com>

src/libcamera/meson.build

@@ -151,7 +151,8 @@ foreach mode, inout_files : controls_mode_files
                                      output : output_file,
                                      command : [gen_controls, '-o', '@OUTPUT@',
                                                 '--mode', mode, '-t', template_file,
-                                                '-r', ranges_file, '@INPUT@'])
+                                                '-r', ranges_file, '@INPUT@'],
+                                     env : py_build_env)
 endforeach
 
 libcamera_public_sources += control_sources