"Extrude region": support new mode available since 2.90

Слиты nikitronn запросил слияние extrude_region_dissolve_ortho в master

Created by: portnov

Blender 2.90 introduced a new flag for "extrude region" operation. It's called a bit mysteriously, "Dissolve Orthogonal Edges"; in fact it can be useful to make complex objects:

Screenshot_20200913_185830

The new flag in the node is available in Blender versions >= 2.90.

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