[PM-29607] Create @bitwarden/subscription (#17997)

* Create @bitwarden/subscription

* Fix changed import in tsconfig.base.json

libs/subscription/src/index.ts

@@ -0,0 +1 @@
+export type Placeholder = unknown;

libs/subscription/src/subscription.spec.ts

@@ -0,0 +1,8 @@
+import * as lib from "./index";
+
+describe("subscription", () => {
+  // This test will fail until something is exported from index.ts
+  it("should work", () => {
+    expect(lib).toBeDefined();
+  });
+});