Add process Builder

[Baptouuuu]

This is for internal use only for now. The concrete way to mock processes will be via innmind/testing.

[codecov]

Codecov Report

❌ Patch coverage is 0% with 44 lines in your changes missing coverage. Please review.
✅ Project coverage is 91.47%. Comparing base (4622d18) to head (1de90e2).
⚠️ Report is 2 commits behind head on develop.

Files with missing lines	Patch %	Lines
src/Server/Process/Builder.php	0.00%	44 Missing ⚠️

Additional details and impacted files

@@              Coverage Diff              @@
##             develop      #26      +/-   ##
=============================================
- Coverage      93.45%   91.47%   -1.99%     
- Complexity       362      375      +13     
=============================================
  Files             57       58       +1     
  Lines           2079     2123      +44     
=============================================
- Hits            1943     1942       -1     
- Misses           136      181      +45     

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