add filter dropdown for categorization keywords

[CollinBeczak]

Similar to the Keywords filter dropdown in the find challenges page, a new dropdown is created to find challenges with matching categorization keywords. A key difference is that the user can manually change what values are stored in the dropdown.

[codecov-commenter]

Codecov Report

Merging #2097 (a63fcc3) into develop (67a08ef) will decrease coverage by 0.15%.
Report is 16 commits behind head on develop.
The diff coverage is 20.00%.

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@@             Coverage Diff             @@
##           develop    #2097      +/-   ##
===========================================
- Coverage    24.96%   24.82%   -0.15%     
===========================================
  Files          638      643       +5     
  Lines        21587    22827    +1240     
  Branches      6567     7168     +601     
===========================================
+ Hits          5389     5666     +277     
- Misses       13574    14293     +719     
- Partials      2624     2868     +244     

Files Changed	Coverage Δ
...ane/ChallengeFilterSubnav/ChallengeFilterSubnav.js	66.66% <ø> (ø)
...s/WithFilteredChallenges/WithFilteredChallenges.js	30.76% <ø> (ø)
src/components/HOCs/WithSearch/WithSearch.js	57.14% <0.00%> (-1.11%)	⬇️
...rc/components/MobileFilterMenu/MobileFilterMenu.js	0.00% <ø> (ø)
...izationKeywords/ChallengeCategorizationKeywords.js	14.28% <14.28%> (ø)
...engeFilterSubnav/FilterByCategorizationKeywords.js	21.05% <21.05%> (ø)
...components/HOCs/WithSearchRoute/WithSearchRoute.js	49.45% <25.00%> (-1.13%)	⬇️

... and 25 files with indirect coverage changes

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