Keep sources of the root of the zoomed-subtree in sync. Closes #1139

[jameshadfield]

We keep track of the root-node of the currently selected subtree within auspice via two pieces of state: idxOfInViewRootNode (redux state) and zoomNode (phylotree state). They were out-of-sync when loading a tree in a zoomed state, which resulted in the inability to zoom out via clicking on a basal branch. This commit fixes this bug.

Long term, it would be better to only store this state in one place. This would involve some refactoring in order to expose the relevant redux state to callbacks such as onBranchClick.

[eharkins]

Looks good, fixes the issue as described in the original issue as well as in at least one other dataset I tested using a query like ?label=clade:DENV1/I. I was confused how to set the label query using something other than a clade name, after reading the view settings doc - perhaps the dataset needs explicitly labeled branches to do that? Happy to help extend the doc if necessary.

Should I open another issue for the long term state consolidation here?

[jameshadfield]

perhaps the dataset needs explicitly labeled branches to do that?

Correct, the dataset JSON itself defines branch labels (a common label key is "clade").

Should I open another issue for the long term state consolidation here?

I feel as this should be noted somewhere, but not as an issue. This is an example of the broader topic of phylotree-state vs redux-state. Sometimes they are duplicated (like here), and sometimes they are separate but in complex ways. Any attempts to address this should be part of a higher-level direction decision.