The sweeper call UpdateParams does not update the exclusive group
property of a pending sweep. This led to anchor outputs being swept
after confirmation with an exclusive group restriction, which is not
necessary.
This commit changes the anchor resolver to not use UpdateParams anymore,
but instead always re-offer the anchor input to the sweeper. The sweeper
is modified so that a re-offering also updates the sweep parameters.
Sweeping anchors and being able to bump the fee was already added in a
previous commit. This commit extends anchor sweeping with an anchor
resolver object that becomes active after the commitment tx confirms.
At that point, the anchors do not serve the purpose of getting the
commitment tranaction confirmed anymore. It is however still possible to
reclaim some of their value if using a low fee rate.
