Extract PLUGIN_ACTION_SCOPE enum from api_plugin.h

Create lightweight plugin_action_scope.h containing only the enum class.
Replace #include <api/api_plugin.h> in eda_draw_frame.h with the new
header and a forward declaration of PLUGIN_ACTION.

This removes transitive includes wx/bmpbndl.h, wx/filename.h and
nlohmann/json_fwd.hpp from 79 TUs.

include/api/api_plugin.h

@@ -29,6 +29,7 @@
 #include <wx/filename.h>
 #include <wx/string.h>
 
+#include <api/plugin_action_scope.h>
 #include <kicommon.h>
 
 
@@ -52,17 +53,6 @@ enum class PLUGIN_RUNTIME_TYPE
 };
 
 
-enum class PLUGIN_ACTION_SCOPE
-{
-    INVALID,
-    PCB,
-    SCHEMATIC,
-    FOOTPRINT,
-    SYMBOL,
-    PROJECT_MANAGER
-};
-
-
 struct PLUGIN_RUNTIME
 {
     bool FromJson( const nlohmann::json& aJson );