push: move outgoing object in the push object
The set of outgoing and common changeset are used by phases to compute the new
common set between local and remote. So we need to move it into the object to
extract the phase sync from the god function.
Note that this information will be used by obsolescence markers too.
Testing that hghave does not crash when checking features
$ "$TESTDIR/hghave" --test-features 2>/dev/null