Maven-invoker: support '--no-snapshot-updates'

Let's add support for --no-snapshot-updates in org.apache.maven.shared.invoker.InvocationRequest

Currently InvocationRequest supports just the -U mvn option which is not enough: it's possible to force the snapshots update or keep default maven policy on this.

But it's not possible to prevent snapshots updates which is highly desired under some circumstances (e.g. for CI reproducibility).

NOTE: I may contribute a PR.