Rename locks to zones

ts/util/Zone.ts

@@ -0,0 +1,22 @@
+// Copyright 2021 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+
+export type ZoneOptions = {
+  readonly pendingSessions?: boolean;
+  readonly pendingUnprocessed?: boolean;
+};
+
+export class Zone {
+  constructor(
+    public readonly name: string,
+    private readonly options: ZoneOptions = {}
+  ) {}
+
+  public supportsPendingSessions(): boolean {
+    return this.options.pendingSessions === true;
+  }
+
+  public supportsPendingUnprocessed(): boolean {
+    return this.options.pendingUnprocessed === true;
+  }
+}