Advertise both link and sync capabilities

Co-authored-by: trevor-signal <131492920+trevor-signal@users.noreply.github.com>

ts/textsecure/Provisioner.ts

@@ -422,7 +422,9 @@ export class Provisioner {
       .toAppUrl({
         uuid,
         pubKey: Bytes.toBase64(cipher.getPublicKey()),
-        capabilities: isLinkAndSyncEnabled(this.#appVersion) ? ['backup'] : [],
+        capabilities: isLinkAndSyncEnabled(this.#appVersion)
+          ? ['backup', 'backup2']
+          : [],
       })
       .toString();