Cleanup: Rename original curve object type enum

This commit renames enums related the "Curve" object type and ID type
to add `_LEGACY` to the end. The idea is to make our aspirations clearer
in the code and to avoid ambiguities between `CURVE` and `CURVES`.

Ref T95355

To summarize for the record, the plans are:
- In the short/medium term, replace the `Curve` object data type with
 `Curves`
- In the longer term (no immediate plans), use a proper data block for
  3D text and surfaces.

Differential Revision: https://developer.blender.org/D14114

source/blender/editors/mesh/editmesh_tools.c

@@ -269,7 +269,8 @@ static void mesh_operator_edgering_props(wmOperatorType *ot,
   RNA_def_property_enum_items(prop, rna_enum_proportional_falloff_curve_only_items);
   RNA_def_property_enum_default(prop, PROP_SMOOTH);
   RNA_def_property_ui_text(prop, "Profile Shape", "Shape of the profile");
-  RNA_def_property_translation_context(prop, BLT_I18NCONTEXT_ID_CURVE); /* Abusing id_curve :/ */
+  RNA_def_property_translation_context(prop,
+                                       BLT_I18NCONTEXT_ID_CURVE_LEGACY); /* Abusing id_curve :/ */
 }
 
 static void mesh_operator_edgering_props_get(wmOperator *op, struct EdgeRingOpSubdProps *op_props)