(core) Add new home page cards

Summary:
New cards on the home page link to useful resources like the welcome
video, tutorial, webinars, and the Help Center. They are shown by
default to new and exisiting users, and may be hidden via a toggle.

Test Plan: Browser tests.

Reviewers: jarek

Reviewed By: jarek

Differential Revision: https://phab.getgrist.com/D4340

test/gen-server/ApiServer.ts

@@ -2301,15 +2301,6 @@ describe('ApiServer', function() {
       assert.deepEqual(resp.data[0].docs.map((doc: any) => doc.name), ['Lightweight CRM']);
       assert.deepEqual(resp.data[1].docs.map((doc: any) => doc.name), ['Expense Report', 'Timesheet']);
 
-      // Make a request to retrieve only the featured (pinned) templates.
-      const resp2 = await axios.get(`${homeUrl}/api/templates/?onlyFeatured=1`, nobody);
-      // Assert that the response includes only pinned documents.
-      assert.equal(resp2.status, 200);
-      assert.lengthOf(resp2.data, 2);
-      assert.deepEqual(resp.data.map((ws: any) => ws.name), ['CRM', 'Invoice']);
-      assert.deepEqual(resp2.data[0].docs.map((doc: any) => doc.name), ['Lightweight CRM']);
-      assert.deepEqual(resp2.data[1].docs, []);
-
       // Add a new document to the CRM workspace, but don't share it with everyone.
       await axios.post(`${homeUrl}/api/workspaces/${crmWsId}/docs`,
         {name: 'Draft CRM Template', isPinned: true}, support);