(core) granular access control in the presence of schema changes

Summary:
 - Support schema changes in the presence of non-trivial ACL rules.
 - Fix update of `aclFormulaParsed` when updating formulas automatically after schema change.
 - Filter private metadata in broadcasts, not just fetches.  Censorship method is unchanged, just refactored.
 - Allow only owners to change ACL rules.
 - Force reloads if rules are changed.
 - Track rule changes within bundle, for clarity during schema changes - tableId and colId changes create a muddle otherwise.
 - Show or forbid pages dynamically depending on user's access to its sections. Logic unchanged, just no longer requires reload.
 - Fix calculation of pre-existing rows touched by a bundle, in the presence of schema changes.
 - Gray out acl page for non-owners.

Test Plan: added tests

Reviewers: dsagal

Reviewed By: dsagal

Differential Revision: https://phab.getgrist.com/D2734

app/client/components/DocComm.ts

@@ -17,6 +17,7 @@ export interface DocUserAction extends CommMessage {
   data: {
     docActions: DocAction[];
     actionGroup: ActionGroup;
+    error?: string;
   };
 }
 
@@ -76,7 +77,15 @@ export class DocComm extends Disposable implements ActiveDocAPI {
     this.listenTo(_comm, 'docShutdown', (m: CommMessage) => {
       if (this.isActionFromThisDoc(m)) { this._isClosed = true; }
     });
-    this.onDispose(() => this._shutdown());
+    this.onDispose(async () => {
+      try {
+        await this._shutdown();
+      } catch (e) {
+        if (!String(e).match(/GristWSConnection disposed/)) {
+          reportError(e);
+        }
+      }
+    });
   }
 
   // Returns the URL params that identifying this open document to the DocWorker