(core) Disallow the combination of Public Edit access and granular ACLs.

Summary:
- When Public Edit access is enabled, Access Rules page shows a warning and
  prevents saving rules.
- When any ACL rules are present, attempts to set Public access to Editor role
  get downgraded to Viewer role, with a warning notification.
- No checks are made on the server side, so the combination may be achieved via
  the API (but we may block it in the future).

Test Plan: Added a test case.

Reviewers: paulfitz

Reviewed By: paulfitz

Differential Revision: https://phab.getgrist.com/D2767

app/client/components/GristDoc.ts

@@ -522,6 +522,14 @@ export class GristDoc extends DisposableWithEvents {
     });
   }
 
+  public hasGranularAccessRules(): boolean {
+    const rulesTable = this.docData.getTable('_grist_ACLRules')!;
+    // To check if there are rules, ignore the default no-op rule created for an older incarnation
+    // of ACLs. It exists in older documents, and is still created for new ones. We detect it by
+    // the use of the deprecated 'permissions' field, and not the new 'permissionsText' field.
+    return rulesTable.numRecords() > rulesTable.filterRowIds({permissionsText: '', permissions: 63}).length;
+  }
+
   private _getToolContent(tool: typeof RightPanelTool.type): IExtraTool|null {
     switch (tool) {
       case 'docHistory': {