Switch to HTTP POST for FHIR Search Requests

[lincmba]

fixes #73

IMPORTANT: Where possible all PRs must be linked to a Github issue

Resolves [link to issue]

Engineer Checklist

• [ ] I have written Unit tests for any new feature(s) and edge cases for bug fixes
• [ ] I have added documentation for any new feature(s) and configuration option(s) on the README.md
• [ ] I have run mvn spotless:check to check my code follows the project's style guide
• [ ] I have run mvn clean test jacoco:report to confirm the coverage report was generated at plugins/target/site/jacoco/index.html
• [ ] I ran mvn clean package right before creating this pull request.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 46.15385% with 7 lines in your changes missing coverage. Please review.

Project coverage is 44.97%. Comparing base (712d495) to head (c11af54). Report is 5 commits behind head on main.

Files	Patch %	Lines
...way/plugins/PractitionerDetailsEndpointHelper.java	44.44%	5 Missing :warning:
...teway/plugins/LocationHierarchyEndpointHelper.java	66.66%	1 Missing :warning:
.../fhir/gateway/plugins/PermissionAccessChecker.java	0.00%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #74 +/- ## ============================================ - Coverage 45.01% 44.97% -0.04% Complexity 130 130 ============================================ Files 16 16 Lines 1213 1225 +12 Branches 146 146 ============================================ + Hits 546 551 +5 - Misses 600 607 +7 Partials 67 67 ```

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[ndegwamartin]

Looks good to me, please add the version bump so that we tag for a release