ValidateTopology does not check correctness of edge.left_face and edge.right_face for isolated edges

[strk]

Similar to lack of containing_face check for nods (#3233) the ValidateTopology also misses checking for left_face and right_face for isolated edges.

[strk]

A way to test this is reported in ​https://trac.osgeo.org/postgis/ticket/4684#comment:19

[Sandro Santilli <strk@…>]

In d138985/git:

Check isolated edges are covered by their left-right faces

Updates existing tests accordingly.
Includes NEWS item.

Closes #4830

[strk]

The fix still misses the case of isolated edge advertised to be in the universal face.

[Sandro Santilli <strk@…>]

In ac60803/git:

Enhance test for topology edge side faces

• Also check non-isolated ones
• Catch universal face containment (only in non-boundary case)

Closes #4830 again

Includes more testcases and updates pre-existing one expectance.

The only missing check now is for dangling edges advertising
the universal face on only ONE side. We cannot easily check
this becase we'd expect such edge to be only contaied by a face
and it will be, even if both sides are in the _same_ face.
This case can only be determined by edge-linking checking
(references #3042)

[Sandro Santilli <strk@…>]

In e0da8d5/git:

Rewrite test for hole containment to really focus on that check

References #4830