Warn user about duplicate processor names - #41 implementation

[luzhanov]

Proposed solution for issue: #41

[codecov]

Codecov Report

Merging #42 into master will increase coverage by 0.41%.
The diff coverage is 83.33%.

@@            Coverage Diff             @@
##           master      #42      +/-   ##
==========================================
+ Coverage   58.36%   58.78%   +0.41%     
==========================================
  Files          18       18              
  Lines         968      985      +17     
  Branches      175      179       +4     
==========================================
+ Hits          565      579      +14     
- Misses        342      343       +1     
- Partials       61       63       +2

Impacted Files	Coverage Δ
...va/com/github/hermannpencole/nifi/config/Main.java	85.29% <100%> (+0.14%)	⬆️
...e/nifi/config/service/ExtractProcessorService.java	89.87% <81.25%> (-2.2%)	⬇️

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