(core) Show usage banners in doc menu of free team sites

Summary:
Also fixes a minor CSS regression in UserManager where the
link to add a team member wasn't shown on a separate row.

Test Plan: Browser tests.

Reviewers: jarek

Reviewed By: jarek

Differential Revision: https://phab.getgrist.com/D3444

app/gen-server/entity/Product.ts

@@ -1,4 +1,4 @@
-import {Features} from 'app/common/Features';
+import {Features, Product as IProduct} from 'app/common/Features';
 import {nativeValues} from 'app/gen-server/lib/values';
 import * as assert from 'assert';
 import {BillingAccount} from 'app/gen-server/entity/BillingAccount';
@@ -67,14 +67,6 @@ export const suspendedFeatures: Features = {
   maxWorkspacesPerOrg: 0,
 };
 
-/**
- * Basic fields needed for products supported by Grist.
- */
-export interface IProduct {
-  name: string;
-  features: Features;
-}
-
 /**
  *
  * Products are a bundle of enabled features.  Most products in