Add a NullAway analysis

              Once we have the JSpecify annotations merged we can add a [Nullaway](https://github.com/uber/NullAway) analysis.

_Originally posted by @mk868 in https://github.com/semver4j/semver4j/issues/308#issuecomment-2541423236_
            