Improve search param extraction flexibility

[jmarchionatto]

What was done:

1. added myExtractResourceLevelParams property to allow extraction of Resource-level search param values
2. extracted some code to be reused to an util class
3. Allowed test to specify a Patient provider to RestServerR4Helper

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[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 83.49%. Comparing base (497b9f2) to head (01fda4c). Report is 112 commits behind head on master.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #6030 +/- ## ============================================ + Coverage 83.39% 83.49% +0.10% - Complexity 26927 27347 +420 ============================================ Files 1681 1703 +22 Lines 103965 105906 +1941 Branches 13189 13365 +176 ============================================ + Hits 86702 88430 +1728 - Misses 11613 11760 +147 - Partials 5650 5716 +66 ```

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