Optimize ensure vertical feature's UX (#4402)

* Change ensure_vertical_shell_thickness to enum value type. Allow users to turn off this feature completely

* add warning to the tooltip for None option

src/libslic3r/PrintConfig.hpp

@@ -176,6 +176,14 @@ enum class SeamScarfType {
     All,
 };
 
+// Orca
+enum EnsureVerticalShellThickness {
+    vsNone,
+    evstCriticalOnly,
+    evstModerate,
+    evstAll,
+};
+
 //Orca
 enum InternalBridgeFilter {
     ibfDisabled, ibfLimited, ibfNofilter
@@ -859,8 +867,7 @@ PRINT_CONFIG_CLASS_DEFINE(
     ((ConfigOptionFloat,                internal_bridge_flow))
     ((ConfigOptionFloat,                bridge_speed))
     ((ConfigOptionFloatOrPercent,       internal_bridge_speed))
-    ((ConfigOptionBool,                 ensure_vertical_shell_thickness))
-    ((ConfigOptionBool,                 reduce_wall_solid_infill))
+    ((ConfigOptionEnum<EnsureVerticalShellThickness>,   ensure_vertical_shell_thickness))
     ((ConfigOptionEnum<InfillPattern>,  top_surface_pattern))
     ((ConfigOptionEnum<InfillPattern>,  bottom_surface_pattern))
     ((ConfigOptionEnum<InfillPattern>, internal_solid_infill_pattern))