Added optional snapping points generation;

[katehryhorenko]

BACKGROUND: ElementInstancesare not serialized as part of the JSON. Explore uses Representation geometry to create snapping points and now it doesn't have data to do it.

DESCRIPTION:

• CreateSnappingPoints method is added to the ElementRepresentation
• SnappingPointsSource property is added to the RepresentationInstance. By default this value is None => no additional geometry will be created
• Snapping points are saved as HYPAR_snapping_points node extension inside glb. But now I'm saving it to each representation node. But there should be a way to keep it at some place (like mesh) and re-use it.
• related to this PR

TESTING:

• I tested it with Unicorn function and with DebugGeometry flag on to be sure that Explore uses only data from the visible representations

FUTURE WORK:

• Add SnappingPointsSource.Glb => Explore will generate snapping points from the Oblect3D edges
• Mode SnappingPoints user data to Mesh Node (or some other reusable place)

REQUIRED:

• [ ] All changes are up to date in CHANGELOG.md.

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