fix: masquerade dropdown not showing current selection (#30)

[kaustavb12]

Description

Cherry-pick from openedx#1434 and #30

All details including testing instructions can be found there.

Other information

Private Ref : BB-9074

[kaustavb12]

Merging without approval since the changes here has already been approved twice in openedx#1434 and #30.

[codecov]

Codecov Report

Attention: Patch coverage is 90.00000% with 1 line in your changes missing coverage. Please review.

Project coverage is 89.48%. Comparing base (cb1a614) to head (3a8c0dd).
Report is 2 commits behind head on asu-moe/redwood-css.

Files with missing lines	Patch %	Lines
...tor-toolbar/masquerade-widget/MasqueradeWidget.jsx	88.88%	1 Missing ⚠️

Additional details and impacted files

@@                   Coverage Diff                   @@
##           asu-moe/redwood-css      #31      +/-   ##
=======================================================
+ Coverage                88.77%   89.48%   +0.70%     
=======================================================
  Files                      306      306              
  Lines                     5256     5258       +2     
  Branches                  1336     1302      -34     
=======================================================
+ Hits                      4666     4705      +39     
+ Misses                     573      536      -37     
  Partials                    17       17              

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