fix(Overlay): let a controller on the overlay dismiss it

[mstijak]

Fixes #1332.

Problem

A controller attached to a Window (or any overlay) could not close it:

class EditorController extends Controller {
  onSave() {
    this.instance.parentOptions.dismiss(); // parentOptions.dismiss was undefined
  }
}

<Window visible={m.editor.visible} controller={EditorController}>…</Window>

The same controller worked when attached to an element inside the window.

Instance.explore copies context.parentOptions onto the instance before the widget's own explore runs. Overlay.explore computes dismiss and pushes it for its children only after that, so the overlay's own instance never received it.

Change

Overlay.explore now assigns the options object it pushes for its children to its own instance as well, so the overlay and its content see the same dismiss. Only the overlay's own instance changes; Button (dismiss) and MsgBox, the other readers of parentOptions, read it on instances inside the overlay.

Tests

New Window.spec.tsx renders an inline window and calls dismiss() from a controller attached to the window and from one inside it, checking that the bound visible becomes false. The first case failed before the change.

• yarn workspace cx run test: 537 passing, 2 pending, 0 failing
• yarn workspace cx run check-types: no errors