Sketcher: AddSymmetric End-to-End point tangency bug fix

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For a while End-to-endpoint tangency is implemented via AngleViaPoint constraint. The code was not recalculating the "value" of the constraint in this case.

This also forces to set the geometry first and constraints afterwards, as the AutoLockTangencyAndPerpty function requires a valid GeoId to operate (not a big deal anyway).

Correction of the condition to allow the symmetry when a single line is mirrored about a point pertaining to a geometric element.