(core) Adding confirmation before remove last widget for a table

Summary:
When last widget for a table is removed, user is informed
about that and can decide between removing the widget and removing
both table and widget

Test Plan: Updated

Reviewers: georgegevoian

Reviewed By: georgegevoian

Differential Revision: https://phab.getgrist.com/D4295

app/client/models/entities/TableRec.ts

@@ -39,6 +39,7 @@ export interface TableRec extends IRowModel<"_grist_Tables"> {
   // If user can select this table in various places.
   // Note: Some hidden tables can still be visible on RawData view.
   isHidden: ko.Computed<boolean>;
+  isSummary: ko.Computed<boolean>;
 
   tableColor: string;
   disableAddRemoveRows: ko.Computed<boolean>;
@@ -68,6 +69,8 @@ export function createTableRec(this: TableRec, docModel: DocModel): void {
   this.primaryTableId = ko.pureComputed(() =>
     this.summarySourceTable() ? this.summarySource().tableId() : this.tableId());
 
+  this.isSummary = this.autoDispose(ko.pureComputed(() => Boolean(this.summarySourceTable())));
+
   this.groupByColumns = ko.pureComputed(() => this.columns().all().filter(c => c.summarySourceCol()));
 
   this.groupDesc = ko.pureComputed(() => {

app/client/models/entities/ViewSectionRec.ts

@@ -93,9 +93,12 @@ export interface ViewSectionRec extends IRowModel<"_grist_Views_section">, RuleO
   // in which case the UI prevents various things like hiding columns or changing the widget type.
   isRaw: ko.Computed<boolean>;
 
-  tableRecordCard: ko.Computed<ViewSectionRec>
+  /** Is this table card viewsection (the one available after pressing spacebar) */
   isRecordCard: ko.Computed<boolean>;
 
+  /** Card record viewSection for associated table (might be the same section) */
+  tableRecordCard: ko.Computed<ViewSectionRec>;
+
   /** True if this section is disabled. Currently only used by Record Card sections. */
   disabled: modelUtil.KoSaveableObservable<boolean>;