bundle2: automatically add 'targetphase' parameter in writenewbundle If we are bundling secret changeset and the bundle will contain phase, we request the changegroup to be applied as secret. It will be useful for next patch as we are now sure that secrets changesets are applied as secret and not applied as draft then forced to secret.

bundle2: support the 'targetphase' parameter for the changegroup part By default unbundled changesets are drafts. We want to reduce the number of phases changes during unbundling by giving the possibility to the bundle to indicate the phase of unbundled changesets. The longer terms goal is to add phase movement tracking in tr.changes and the 'retractboundary' call is making it more complicated than we want.