Adds keyboard shortcuts for panning and zooming on a focused view

[carolinebridge]

Adds keyboard shortcuts for:

Scroll with LeftArrow and RightArrow
Zoom with Shift + (UpArrow || DownArrow)

• put the event listener in the AppFocus mixin, wondering if that's the best place for it
• not sure if I like shift + arrow for zoom, I think ctrl/cmd is more intuitive but would like to hear thoughts

Waiting for the focus PR to be merged before this one into main

Partially resolves #927

[codecov]

Codecov Report

Merging #3832 (4da760a) into main (6fb9daa) will increase coverage by 0.02%.
Report is 8 commits behind head on main.
The diff coverage is 52.94%.

@@            Coverage Diff             @@
##             main    #3832      +/-   ##
==========================================
+ Coverage   64.45%   64.47%   +0.02%     
==========================================
  Files        1003     1003              
  Lines       29782    29799      +17     
  Branches     7146     7151       +5     
==========================================
+ Hits        19196    19213      +17     
  Misses      10423    10423              
  Partials      163      163              

Files Changed	Coverage Δ
...s/linear-genome-view/src/LinearGenomeView/model.ts	83.16% <52.94%> (-1.10%)	⬇️

... and 2 files with indirect coverage changes

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[garrettjstevens]

I think ctrl+up/down is more intuitive for zoom than shift.

I noticed that if the side widget has a horizontal scroll and is in focus from a browser perspective (not from a JBrowse perspective) the left/right will also scroll the widget.

[cmdcolin]

i might agree with ctrl+up/down because we have ctrl+scroll for zoom too

[carolinebridge]

Added ctrl/meta keys to the left and right operations --

• consistent with the other nav operations
• allows the user to still scroll up and down on widgets / in the main views container if they wish if they use the arrows without pressing ctrl/meta
• deeply nested preventDefault so if the user has the view in focus it doesn't override the default for every keystroke (e.g. cmd + r for refresh would be overridden if it was one level outside of where i placed it)

[cmdcolin]

I added a 'removeEventHandler' using an addDisposer. I think should be good to go. it is a little tricky, becuase I was pressing "ctrl+down" multiple times but it would not zoom out a lot. that is because it is actively doing an animation. it may be good to find a workaround for this...i think it would be good to 'quickly zoom out' a multiple rapid ctrl+down key presses.

[cmdcolin]

might not be necessary to hold up the PR though. can merge :)