Hide the OpenSeadragon navigator while drawing (#1514)

[blms]

In this PR

Per #1514:

• Prevent the OSD navigator from getting in the way of drawing polygons and rectangles, by hiding it during drawing

[codecov]

Codecov Report

Merging #1524 (d7d6934) into develop (214fbf9) will increase coverage by 0.03%.
Report is 3 commits behind head on develop.
The diff coverage is n/a.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #1524      +/-   ##
===========================================
+ Coverage    98.43%   98.47%   +0.03%     
===========================================
  Files          221      221              
  Lines        12525    12833     +308     
===========================================
+ Hits         12329    12637     +308     
  Misses         196      196