Fix #100659: "Add F-Curve Modifier" applies only to Active F-Curve

In most places where it appears in a menu, the operator would already
apply to all selected F-Curves. Now it is done consistently and explicitly
from all menu items. The default of the operator is now also set to 'all
selected', so that it also behaves like that when called from the operator
search menu.

scripts/startup/bl_ui/space_graph.py

@@ -252,7 +252,7 @@ class GRAPH_MT_key(Menu):
 
         layout.separator()
         layout.operator_menu_enum("graph.keyframe_insert", "type")
-        layout.operator_menu_enum("graph.fmodifier_add", "type")
+        layout.operator_menu_enum("graph.fmodifier_add", "type").only_active = False
         layout.operator("graph.sound_bake")
 
         layout.separator()

source/blender/editors/space_graph/graph_edit.c

@@ -2843,7 +2843,7 @@ void GRAPH_OT_fmodifier_add(wmOperatorType *ot)
   ot->prop = prop;
 
   RNA_def_boolean(
-      ot->srna, "only_active", 1, "Only Active", "Only add F-Modifier to active F-Curve");
+      ot->srna, "only_active", false, "Only Active", "Only add F-Modifier to active F-Curve");
 }
 
 /** \} */