feat: deprecate notification tray in learning header

[awais-ansari]

INF-993

• Remove notification module from openedx header because there is a plan to extract this module to npm package.

[codecov]

Codecov Report

Patch coverage: 75.00% and project coverage change: -17.54% ⚠️

Comparison is base (4b89e75) 78.79% compared to head (018ca18) 61.25%.

Additional details and impacted files

@@             Coverage Diff             @@
##           master     #379       +/-   ##
===========================================
- Coverage   78.79%   61.25%   -17.54%     
===========================================
  Files          31       16       -15     
  Lines         599      302      -297     
  Branches      112       70       -42     
===========================================
- Hits          472      185      -287     
+ Misses        124      115        -9     
+ Partials        3        2        -1     

Files Changed	Coverage Δ
src/learning-header/AuthenticatedUserDropdown.jsx	83.33% <ø> (-8.98%)	⬇️
src/learning-header/LearningHeader.jsx	92.85% <75.00%> (ø)

... and 1 file with indirect coverage changes

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