shift,option+mouseWheel zoom bugs in entropy panel

[eharkins]

Current Behavior
Breaking this out from #1145

Zooming the entropy panel by the ctrl+mouseWheel does not update the URL query. Not sure what (if any) dispatches are occurring on this action

relevant code here

It looks like the keys that allow you to zoom on the entropy panel by scrolling are actually shift and option.

shift + scrolling doesn't update the zoom visually or in the query for me.
option + scrolling updates the zoom visually but not in the query as described in #1145

Expected behavior
If it is working, the bar should change in size (and the query should update with gmin and/or gmax).

How to reproduce
Steps to reproduce the current behavior:

1. Go to https://nextstrain.org/flu/seasonal/h3n2/ha/2y

2. On the entropy panel, hold either option or shift key and scroll while the mouse is over the grey bar:
   

3. see expected behavior. the bug looks like either nothing happening or query not updating

Your environment: if browsing Nextstrain online

• FWIW I am using external mouse not laptop touch pad.

[hangzho]

Hi @eharkins, I'm new to this project. I've created a potential solution in my PR to fix this issue. Let me know if you have any questions or suggestions. Thanks.