Add ability to perform some logic during worker's lifecycle

[TechnoBerry]

Closes #4

[codecov-commenter]

Codecov Report

Merging #41 (7a15e16) into master (a2fed08) will decrease coverage by 0.70%.
The diff coverage is 55.55%.

❗ Current head 7a15e16 differs from pull request most recent head b510978. Consider uploading reports for the commit b510978 to get more accurate results

@@            Coverage Diff             @@
##           master      #41      +/-   ##
==========================================
- Coverage   94.38%   93.68%   -0.71%     
==========================================
  Files          33       33              
  Lines         374      380       +6     
  Branches        7        7              
==========================================
+ Hits          353      356       +3     
- Misses         19       22       +3     
  Partials        2        2              

Impacted Files	Coverage Δ
src/Camunda.Worker/CamundaWorkerBuilder.cs	88.57% <0.00%> (-11.43%)	⬇️
...c/Camunda.Worker/Execution/DefaultCamundaWorker.cs	100.00% <100.00%> (+3.57%)	⬆️
src/Camunda.Worker/ServiceCollectionExtensions.cs	100.00% <100.00%> (ø)

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