migrate category sync utils

[salander85]

Additionally added 2 more test classes for other utils which haven't been migrated yet.

JIRA: https://commercetools.atlassian.net/browse/DEVX-82

[codecov-commenter]

Codecov Report

Merging #974 (586ec38) into java-sdk-v2-category-sync-migration (9176852) will increase coverage by 0.62%.
The diff coverage is 97.56%.

@@                            Coverage Diff                            @@
##             java-sdk-v2-category-sync-migration     #974      +/-   ##
=========================================================================
+ Coverage                                  95.62%   96.25%   +0.62%     
- Complexity                                  3957     3990      +33     
=========================================================================
  Files                                        345      347       +2     
  Lines                                      11566    11613      +47     
  Branches                                     699      700       +1     
=========================================================================
+ Hits                                       11060    11178     +118     
+ Misses                                       401      332      -69     
+ Partials                                     105      103       -2     

Impacted Files	Coverage Δ
...mmercetools/sync/sdk2/commons/utils/SyncUtils.java	100.00% <ø> (ø)
...gories/utils/CategoryReferenceResolutionUtils.java	91.66% <91.66%> (ø)
.../sync/sdk2/categories/utils/CategorySyncUtils.java	100.00% <100.00%> (ø)
...nc/sdk2/commons/utils/AssetsUpdateActionUtils.java	100.00% <100.00%> (+8.86%)	⬆️
...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 2 files with indirect coverage changes

[lojzatran]

Good job 🥳