Fix building docs with PyQt6

[Czaki]

References and relevant issues

Unlock napari/shared-workflows#29

Description

The build docs against PyQt6 fails with such warnings (and we treat warnings as errors).

docstring of napari.qt.QtToolTipLabel.Shadow.from_bytes:9: WARNING: Inline interpreted text or phrase reference start-string without end-string. [docutils]
docstring of napari.qt.QtToolTipLabel.Shadow.to_bytes:8: WARNING: Inline interpreted text or phrase reference start-string without end-string. [docutils]
docstring of napari.qt.QtToolTipLabel.Shape.from_bytes:9: WARNING: Inline interpreted text or phrase reference start-string without end-string. [docutils]
docstring of napari.qt.QtToolTipLabel.Shape.to_bytes:8: WARNING: Inline interpreted text or phrase reference start-string without end-string. [docutils]
docstring of napari.qt.QtViewer.Shadow.from_bytes:9: WARNING: Inline interpreted text or phrase reference start-string without end-string. [docutils]
docstring of napari.qt.QtViewer.Shadow.to_bytes:8: WARNING: Inline interpreted text or phrase reference start-string without end-string. [docutils]
docstring of napari.qt.QtViewer.Shape.from_bytes:9: WARNING: Inline interpreted text or phrase reference start-string without end-string. [docutils]
docstring of napari.qt.QtViewer.Shape.to_bytes:8: WARNING: Inline interpreted text or phrase reference start-string without end-string. [docutils]
docstring of napari.qt.QtViewerButtons.Shadow.from_bytes:9: WARNING: Inline interpreted text or phrase reference start-string without end-string. [docutils]
docstring of napari.qt.QtViewerButtons.Shadow.to_bytes:8: WARNING: Inline interpreted text or phrase reference start-string without end-string. [docutils]
docstring of napari.qt.QtViewerButtons.Shape.from_bytes:9: WARNING: Inline interpreted text or phrase reference start-string without end-string. [docutils]
docstring of napari.qt.QtViewerButtons.Shape.to_bytes:8: WARNING: Inline interpreted text or phrase reference start-string without end-string. [docutils]

This PR uses our machinery to filter out problematic methods.

It improves the Qt filter mechanism to not filter outside the napari.qt module

[TimMonko]

@napari-bot make docs

[Czaki]

@TimMonko it builds

[TimMonko]

🍻 thanks for the ping! So glad to have this rolling in.
ping me when next PR is ready