(core) Tweak navbar, breadcrumbs, and sign-in buttons

Summary:
The changes are intended to smooth over some sharp edges when a signed-out user
is using Grist (particularly while on the templates site).

Test Plan: Browser tests.

Reviewers: paulfitz

Reviewed By: paulfitz

Differential Revision: https://phab.getgrist.com/D3957

app/common/UserAPI.ts

@@ -20,7 +20,7 @@ import {
   WebhookSummaryCollection,
   WebhookUpdate
 } from 'app/common/Triggers';
-import {addCurrentOrgToPath} from 'app/common/urlUtils';
+import {addCurrentOrgToPath, getGristConfig} from 'app/common/urlUtils';
 import omitBy from 'lodash/omitBy';
 
 
@@ -92,11 +92,14 @@ export function getOrgName(org: Organization): string {
 }
 
 /**
- * Returns whether the given org is the templates org, which contains the public templates.
+ * Returns whether the given org is the templates org, which contains the public
+ * templates and tutorials.
  */
-export function isTemplatesOrg(org: Organization): boolean {
-  // TODO: It would be nice to have a more robust way to detect the templates org.
-  return org.domain === 'templates' || org.domain === 'templates-s';
+export function isTemplatesOrg(org: {domain: Organization['domain']}|null): boolean {
+  if (!org) { return false; }
+
+  const {templateOrg} = getGristConfig();
+  return org.domain === templateOrg;
 }
 
 export type WorkspaceProperties = CommonProperties;
@@ -117,7 +120,7 @@ export interface Workspace extends WorkspaceProperties {
   isSupportWorkspace?: boolean;
 }
 
-export type DocumentType = 'tutorial';
+export type DocumentType = 'tutorial'|'template';
 
 // Non-core options for a document.
 // "Non-core" means bundled into a single options column in the database.

app/common/gristUrls.ts

@@ -80,6 +80,7 @@ export const commonUrls = {
   plans: "https://www.getgrist.com/pricing",
   sproutsProgram: "https://www.getgrist.com/sprouts-program",
   contact: "https://www.getgrist.com/contact",
+  templates: 'https://www.getgrist.com/templates',
   community: 'https://community.getgrist.com',
   functions: 'https://support.getgrist.com/functions',
   formulaSheet: 'https://support.getgrist.com/formula-cheat-sheet',
@@ -647,6 +648,9 @@ export interface GristLoadConfig {
 
   // The Grist deployment type (e.g. core, enterprise).
   deploymentType?: GristDeploymentType;
+
+  // The org containing public templates and tutorials.
+  templateOrg?: string|null;
 }
 
 export const Features = StringUnion(