Move middle name fieldnames to Identity constants

src/services/autofill.service.ts

@@ -610,7 +610,7 @@ export default class AutofillService implements AutofillServiceInterface {
                     fillFields.firstName = f;
                     break;
                 } else if (!fillFields.middleName && this.isFieldMatch(f[attr],
-                    ['m-name', 'middle-name', 'additional-name', 'middle-initial', 'middle-n', 'middle-i'])) {
+                    IdentityAutoFillConstants.MiddlenameFieldNames)) {
                     fillFields.middleName = f;
                     break;
                 } else if (!fillFields.lastName && this.isFieldMatch(f[attr],

src/services/autofillConstants.ts

@@ -200,6 +200,15 @@ export class IdentityAutoFillConstants {
     "vorname",
   ];
 
+  static readonly MiddlenameFieldNames: string[] = [
+    "m-name",
+    "middle-name",
+    "additional-name",
+    "middle-initial",
+    "middle-n",
+    "middle-i",
+  ];
+
   static readonly LastnameFieldNames: string[] = [
     // English
     "l-name",