Minor correction on syntax coloring

The semantics were changed a bit in https://github.com/fsprojects/VisualFSharpPowerTools/commit/30a73458fd890e20ca17f84097abf6c38a957eaa. The correction is that we construct the span on the old snapshot and translate it to a span on the new snapshot.
No. It has always been done this way for a long time. See https://github.com/fsprojects/VisualFSharpPowerTools/blob/1965b503c7444a812d04929ce5fce528f6607e74/src/FSharpVSPowerTools.Logic/SyntaxConstructClassifier.fs#L163-L164 for example. The regression has been introduced here https://github.com/fsprojects/VisualFSharpPowerTools/blob/30a73458fd890e20ca17f84097abf6c38a957eaa/src/FSharpVSPowerTools.Logic/SyntaxConstructClassifier.fs#L165-L166.