Chain filters cpu utilization (#16817)

* Breadth first search on graph for chain filters

- abandons at max-depth and looks in breadth first fashion rather than
descending as far as possible on each possible path

* Add loop detection

not actually fooled by loops since we abandon after a certain path
length. But will remove some false starts before they have to be
killed by the path length check.

* Add seen optimization of nodes

We reach nodes in the shortest path possible, so keep a list of nodes
visited and don't revisit them: we got to them as fast as possible,
and once there, there's no new nodes that we can see from that vantage
point.

This allows a serious speedup and should hopefully fully resolve the
cpu issues seen by some.

* alignment