(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/common/TableData.ts

@@ -8,12 +8,16 @@ import {
 import {getDefaultForType} from 'app/common/gristTypes';
 import {arrayRemove, arraySplice, getDistinctValues} from 'app/common/gutil';
 import {SchemaTypes} from "app/common/schema";
-import {UIRowId} from 'app/common/UIRowId';
 import isEqual = require('lodash/isEqual');
 import fromPairs = require('lodash/fromPairs');
 
 export interface ColTypeMap { [colId: string]: string; }
 
+// This is the row ID used in the client, but it's helpful to have available in some common code
+// as well, which is why it's declared in app/common. Note that for data actions and stored data,
+// 'new' is not used.
+export type UIRowId = number | 'new';
+
 type UIRowFunc<T> = (rowId: UIRowId) => T;
 
 interface ColData {