Island: Split up utils in repository

[VakarisZ]

What does this PR do?

Splits up utilities in repositories package

Add any further explanations here.

PR Checklist

• Have you added an explanation of what your changes do and why you'd like to include them?
• Is the TravisCI build passing?
• Was the CHANGELOG.md updated to reflect the changes?
• Was the documentation framework updated to reflect the changes?
• Have you checked that you haven't introduced any duplicate code?

Testing Checklist

• Added relevant unit tests?
• Have you successfully tested your changes locally? Elaborate:

  Tested by running unit tests

• If applicable, add screenshots or log transcripts of the feature working

[codecov]

Codecov Report

Base: 64.19% // Head: 64.20% // Increases project coverage by +0.00% 🎉

Coverage data is based on head (44d61c1) compared to base (5e903a8).
Patch has no changes to coverable lines.

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #2792   +/-   ##
========================================
  Coverage    64.19%   64.20%           
========================================
  Files          404      406    +2     
  Lines        11569    11572    +3     
========================================
+ Hits          7427     7430    +3     
  Misses        4142     4142           

Impacted Files	Coverage Δ
...nkey/monkey/monkey_island/cc/repositories/utils.py
...d/cc/repositories/utils/machine_repository_init.py	57.14% <0.00%> (ø)
...ey/monkey_island/cc/repositories/utils/__init__.py	100.00% <0.00%> (ø)
...nkey_island/cc/repositories/utils/mongo_encoder.py	100.00% <0.00%> (ø)

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[ilija-lazoroski]

Shorten the import for mongo_encoder.

[VakarisZ]

DOT_REPLACEMENT is not part of the package interface, because it's not used (and probably shouldn't be used) outside of the package