Refactoring UI Components and adding more stores

[tmeasday]

cc @domyen @ndelangen

Re-target this PR to next once #5372 is merged

[codecov]

Codecov Report

Merging #5404 into next will increase coverage by 0.2%.
The diff coverage is 94.44%.

@@            Coverage Diff            @@
##             next    #5404     +/-   ##
=========================================
+ Coverage   30.84%   31.05%   +0.2%     
=========================================
  Files         622      625      +3     
  Lines        9158     9180     +22     
  Branches     1302     1302             
=========================================
+ Hits         2825     2851     +26     
+ Misses       5687     5685      -2     
+ Partials      646      644      -2

Impacted Files	Coverage Δ
.../ui/src/components/nav/NotificationList.stories.js	100% <100%> (ø)
.../ui/src/components/nav/NotificationItem.stories.js	100% <100%> (ø)
lib/ui/src/components/nav/nav.js	100% <100%> (+12.5%)	⬆️
lib/ui/src/components/nav/NotificationList.js	83.33% <83.33%> (ø)
lib/ui/src/components/nav/NotificationItem.js	92.3% <92.3%> (ø)

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