Chore: convert "unnamed" into constant

- "Unnamed/Unknown" simplified into just "Unnamed"
- Phrase variations have their own constants

src/libs/util.ts

@@ -33,6 +33,7 @@ import { logger } from "../utils/logger";
 import { PlatformServiceFactory } from "../services/PlatformServiceFactory";
 import { IIdentifier } from "@veramo/core";
 import { DEFAULT_ROOT_DERIVATION_PATH } from "./crypto";
+import { UNNAMED_USER } from "@/constants/entities";
 
 // Consolidate this with src/utils/PlatformServiceMixin.mapQueryResultToValues
 function mapQueryResultToValues(
@@ -192,7 +193,7 @@ export const nameForContact = (
 ): string => {
   return (
     (contact?.name as string) ||
-    (capitalize ? "This" : "this") + " unnamed user"
+    (capitalize ? "This" : "this") + " " + UNNAMED_USER
   );
 };