Add frontend for group invitations

For #887

src/graphql/invitations.ts

@@ -0,0 +1,37 @@
+import gql from "graphql-tag";
+
+export const GROUP_INVITATIONS_LIST = gql`
+  query ListInvitation($groupId: ID!) {
+    listInvitations(groupId: $groupId) {
+      label
+      token
+    }
+  }
+`;
+
+export const GROUP_INVITATIONS_CREATE = gql`
+  mutation CreateInvitation($groupId: ID!, $label: String) {
+    createInvitation(groupId: $groupId, label: $label) {
+      label
+      token
+    }
+  }
+`;
+
+export const GROUP_INVITATIONS_UPDATE = gql`
+  mutation UpdateInvitation($groupId: ID!, $token: String!, $label: String) {
+    updateInvitation(groupId: $groupId, token: $token, label: $label) {
+      label
+      token
+    }
+  }
+`;
+
+export const GROUP_INVITATIONS_DELETE = gql`
+  mutation DeleteInvitation($groupId: ID!, $token: String!) {
+    deleteInvitation(groupId: $groupId, token: $token) {
+      label
+      token
+    }
+  }
+`;