deduplicate semantic for StaticCtorDeclaration/StaticDtorDeclaration

[thewilsonator]

they are almost identical. Alternative implementation is to make them descend from a common type.

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[RazvanN7]

Maybe a better name for this function would be "statiCtorDtorsemantic"? In the name you've chosen it's easy to miss the C or the D.

[thewilsonator]

it should be obvious it is not like the other visits: it is not override and it is not named visit