Draft: implement Draft_AddToLayer command

Fixes #17323.

* Instead of extending Draft_AddToGroup a separate, but similar, command has been created.
* The three "Add to" tools have been grouped in the menu and the toolbar.
* The Draft_AddToGroup icon is provisional. Ideally the "Add to" tools should have related icons (it would then be nice to keep the trowel image in some way for the construction group). Draft_AddNamedGroup.svg and Draft_SelectGroup.svg probably also need to be updated in that context.

src/Mod/Draft/draftutils/init_tools.py

@@ -114,9 +114,11 @@ def get_draft_utility_commands_menu():
             "Draft_Layer",
             "Draft_LayerManager",
             "Draft_AddNamedGroup",
-            "Draft_AddToGroup",
             "Draft_SelectGroup",
             "Draft_ToggleConstructionMode",
+            "Separator",
+            "Draft_AddToLayer",
+            "Draft_AddToGroup",
             "Draft_AddConstruction",
             "Separator",
             "Draft_ToggleDisplayMode",
@@ -132,8 +134,9 @@ def get_draft_utility_commands_toolbar():
     """Return the utility commands list for the toolbar."""
     return ["Draft_LayerManager",
             "Draft_AddNamedGroup",
-            "Draft_AddToGroup",
             "Draft_SelectGroup",
+            "Draft_AddToLayer",
+            "Draft_AddToGroup",
             "Draft_AddConstruction",
             "Draft_ToggleDisplayMode",
             "Draft_WorkingPlaneProxy"]
@@ -169,10 +172,13 @@ def get_draft_context_commands():
             "Draft_ApplyStyle",
             "Separator",
             "Draft_Layer",
+            "Draft_LayerManager",
             "Draft_AddNamedGroup",
-            "Draft_AddToGroup",
             "Draft_SelectGroup",
             "Draft_ToggleConstructionMode",
+            "Separator",
+            "Draft_AddToLayer",
+            "Draft_AddToGroup",
             "Draft_AddConstruction",
             "Separator",
             "Draft_ToggleDisplayMode",