fix error is OfferDialog where assignment to a project was missed, plus some refactors

src/components/OfferDialog.vue

@@ -6,7 +6,7 @@
         type="text"
         data-testId="inputDescription"
         class="block w-full rounded border border-slate-400 mb-2 px-3 py-2"
-        placeholder="Description, prerequisites, terms, etc."
+        placeholder="Description of what is offered"
         v-model="description"
       />
       <div class="flex flex-row mt-2">
@@ -235,6 +235,7 @@ export default class OfferDialog extends Vue {
         description,
         amount,
         unitCode,
+        "",
         expirationDateInput,
         this.recipientDid,
         this.projectId,