refactor: replace global focusin listener with focusout check

[web-padawan]

Description

Depends on #7855

This PR simplifies the logic in vaadin-grid-pro that was specifically introduced for handling moving focus from the <input> to the vaadin-date-picker-overlay-content, see the following PRs in the old repo:

• Fix focusout handling for editor components with overlay vaadin-grid-pro#96
• Do not stop editing when interacting within the same cell. vaadin-grid-pro#97
• fix: change timing for the stopEdit() call on focusOut cell editor vaadin-grid-pro#165

Type of change

• Refactor

Note

I have moved one of the tests to the new test suite for grid-pro with custom editors and removed the old integration test. It was using rather complicated setup with vaadin-dialog since the workaround was specifically checking for the tag name of the overlay where the focus is moving, and this is no longer the case (we now rely on _shouldRemoveFocus() instead).

[web-padawan]

UPD: looks like there might be a regression here when wrapping vaadin-date-picker in vaadin-custom-field.
This could be also reproduced by using the setup from the old test where div is used as a wrapper.

I'll investigate if we could somehow detect this case to get the actual editor component for the given cell (currently, for the custom editor type the cell._content.firstElementChild is used and at least on focusout it's wrong).

[sonarcloud]

Quality Gate failed

Failed conditions
24.6% Duplication on New Code (required ≤ 3%)

See analysis details on SonarCloud

[vursen]

LGTM.

This refactoring appears to eliminate the need for the internal-tab event. I tested custom-field as a custom editor in grid-pro, and tabbing between its sub-fields now works correctly even without that event in place. Should we consider removing support for this event from grid-pro and deprecating it in custom-field?

[web-padawan]

Should we consider removing support for this event from grid-pro and deprecating it in custom-field?

Good point. I'll create a separate PR for it and add custom-field to integration tests to verify it's not needed.