support --unlock-present adjustment of view branches

support --unlock-present adjustment of view branches

When generating the view, check if the key is present.

When syncing in a view branch with an adjustment, run adjustedBranchRefreshFull
the same as is done when syncing in other adjusted branches. This is
needed because the docs for git-annex adjust --unlock-present suggest
using git-annex sync to update the branch when annex.adjustedbranchrefresh
is not set.

Note that, with annex.adjustedbranchrefresh set, it just works! The
adjusted branch gets updated in the usual way and it doesn't matter that
there's a view branch underneath.

And of course, re-running git-annex adjut --unlock-present also works,
as suggested in the docs.

Sponsored-by: Erik Bjäreholt on Patreon