Edit library footprint command

Provides missing PCB_ACTION for the edit library footprint command.  This is
needed for python control of the command

Fixes https://gitlab.com/kicad/code/kicad/issues/9454

pcbnew/tools/board_editor_control.cpp

@@ -1473,7 +1473,10 @@ int BOARD_EDITOR_CONTROL::EditFpInFpEditor( const TOOL_EVENT& aEvent )
 
     auto editor = (FOOTPRINT_EDIT_FRAME*) editFrame->Kiway().Player( FRAME_FOOTPRINT_EDITOR, true );
 
-    editor->LoadFootprintFromBoard( fp );
+    if( aEvent.IsAction( &PCB_ACTIONS::editFpInFpEditor ) )
+        editor->LoadFootprintFromBoard( fp );
+    else if( aEvent.IsAction( &PCB_ACTIONS::editLibFpInFpEditor ) )
+        editor->LoadFootprintFromLibrary( fp->GetFPID() );
 
     editor->Show( true );
     editor->Raise();        // Iconize( false );
@@ -1565,6 +1568,7 @@ void BOARD_EDITOR_CONTROL::setTransitions()
     Go( &BOARD_EDITOR_CONTROL::DrillOrigin,            PCB_ACTIONS::drillOrigin.MakeEvent() );
 
     Go( &BOARD_EDITOR_CONTROL::EditFpInFpEditor,       PCB_ACTIONS::editFpInFpEditor.MakeEvent() );
+    Go( &BOARD_EDITOR_CONTROL::EditFpInFpEditor,       PCB_ACTIONS::editLibFpInFpEditor.MakeEvent() );
 
     // Other
     Go( &BOARD_EDITOR_CONTROL::ToggleLockSelected,     PCB_ACTIONS::toggleLock.MakeEvent() );

pcbnew/tools/pcb_actions.cpp

@@ -234,6 +234,13 @@ TOOL_ACTION PCB_ACTIONS::editFpInFpEditor( "pcbnew.EditorControl.EditFpInFpEdito
         _( "Opens the selected footprint in the Footprint Editor" ),
         BITMAPS::module_editor );
 
+TOOL_ACTION PCB_ACTIONS::editLibFpInFpEditor( "pcbnew.EditorControl.EditLibFpInFpEditor",
+        AS_GLOBAL,
+        MD_CTRL + MD_SHIFT + 'E', "",
+        _( "Edit Library Footprint..." ),
+        _( "Opens the selected footprint in the Footprint Editor" ),
+        BITMAPS::module_editor );
+
 TOOL_ACTION PCB_ACTIONS::getAndPlace( "pcbnew.InteractiveEdit.FindMove",
         AS_GLOBAL,
         'T', LEGACY_HK_NAME( "Get and Move Footprint" ),

pcbnew/tools/pcb_actions.h

@@ -344,6 +344,8 @@ public:
     static TOOL_ACTION runDRC;
 
     static TOOL_ACTION editFpInFpEditor;
+    static TOOL_ACTION editLibFpInFpEditor;
+
     static TOOL_ACTION showLayersManager;
     static TOOL_ACTION showPythonConsole;