DEVX-79 migrate CategoryReferenceResolutionUtils

[lojzatran]

Summary

JIRA: https://commercetools.atlassian.net/browse/DEVX-79

Boy-scout change: I updated the method getResourceIdentifierWithKey() to return a specific ResourceIdentifier type instead of a generic ResourceIdentifier and then have to cast it.

[codecov-commenter]

Codecov Report

Merging #971 (85809a3) into java-sdk-v2-category-sync-migration (9176852) will increase coverage by 0.00%.
The diff coverage is 96.66%.

@@                          Coverage Diff                           @@
##             java-sdk-v2-category-sync-migration     #971   +/-   ##
======================================================================
  Coverage                                  95.62%   95.63%           
- Complexity                                  3957     3962    +5     
======================================================================
  Files                                        345      346    +1     
  Lines                                      11566    11592   +26     
  Branches                                     699      700    +1     
======================================================================
+ Hits                                       11060    11086   +26     
+ Misses                                       401      400    -1     
- Partials                                     105      106    +1     

Impacted Files	Coverage Δ
...mmercetools/sync/sdk2/commons/utils/SyncUtils.java	100.00% <ø> (ø)
...gories/utils/CategoryReferenceResolutionUtils.java	91.66% <91.66%> (ø)
...mons/utils/CustomTypeReferenceResolutionUtils.java	100.00% <100.00%> (ø)
...ercetools/sync/sdk2/products/utils/PriceUtils.java	91.66% <100.00%> (ø)
...roducts/utils/ProductReferenceResolutionUtils.java	98.30% <100.00%> (+0.04%)	⬆️

... and 1 file with indirect coverage changes

[salander85]

Good work :)