(core) Fixing cursor position for filtered linked section.

Summary:
In a selector table, when a selected row is filtered out of view, linked widgets should update based on the newly selected row.
There were a few bugs that contributed to this wrong behavior:
- Gridview wasn't subscribing to the current row id, and the row with id 'new' was being converted to the first row
- Cursor was keeping track of the currently selected row id, it was hiding a problem behind the proper rowIndex
- Undo/redo somehow leveraged the wrong rowId from the cursor during the position restore.

The `No data` text was also changed to be more meaningful.

Test Plan: Added and updated.

Reviewers: georgegevoian

Reviewed By: georgegevoian

Differential Revision: https://phab.getgrist.com/D3937

app/client/components/ActionLog.ts

@@ -78,12 +78,13 @@ export class ActionLog extends dispose.Disposable implements IDomComponent {
     this._displayStack = koArray<ActionGroupWithState>();
 
     // Computed for the tableId of the table currently being viewed.
-    if (!this._gristDoc) {
-      this._selectedTableId = this.autoDispose(ko.computed(() => ""));
-    } else {
-      this._selectedTableId = this.autoDispose(ko.computed(
-        () => this._gristDoc!.viewModel.activeSection().table().tableId()));
-    }
+    this._selectedTableId = this.autoDispose(ko.computed(() => {
+      if (!this._gristDoc || this._gristDoc.viewModel.isDisposed()) { return ""; }
+      const section = this._gristDoc.viewModel.activeSection();
+      if (!section || section.isDisposed()) { return ""; }
+      const table = section.table();
+      return table && !table.isDisposed() ? table.tableId() : "";
+    }));
   }
 
   public buildDom() {