Fix for to ensure selectedBy Avatar is not obscured in NavItem

[deanhannigan]

Description

If a source name was too long it would push the selectedBy Avatar out of view.

• Source names should now truncate with an ellipsis if too long for the NavItem to display.
• Hover text has been added to ensure users can still see the entire resource title
• The Avatar should always remain in view

Screenshots

[codecov-commenter]

Codecov Report

Merging #11889 (9b4201f) into master (762581f) will increase coverage by 0.06%.
Report is 4 commits behind head on master.
The diff coverage is n/a.

❗ Current head 9b4201f differs from pull request most recent head 56c3cb0. Consider uploading reports for the commit 56c3cb0 to get more accurate results

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@@            Coverage Diff             @@
##           master   #11889      +/-   ##
==========================================
+ Coverage   67.87%   67.94%   +0.06%     
==========================================
  Files         585      585              
  Lines       21858    21755     -103     
  Branches     4406     4366      -40     
==========================================
- Hits        14836    14781      -55     
+ Misses       6495     6452      -43     
+ Partials      527      522       -5     

see 28 files with indirect coverage changes

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[aptkingston]

LGTM!