Use query parameters in GET requests for filtering

[stollr]

currently this is done with json/body params. It is working, because guzzle magically turns body params into query params when doing GET requests, but imho this is not clean and we should not rely on this behaviour.

[DumbergerL]

I have some Integration-Tests that are failing with the changes. It is probably just a thing with my data-constelation but i dont have time right now to check.

I hope i can review this PR in depth next week.

[DumbergerL]

PermissionRequestTest: ✅

• fixed data in testata.ini

PublicGroupRequestTest: ✅

• fixed data in testdata.ini
• remove this line because we cannot asume that the GroupCategory and TargetGroup is not null.

  churchtools-api/tests/integration/Requests/PublicGroupRequestTest.php

  Line 49 in 114d4db

  $this->assertNotNull($foundGroup->getInformation()->getGroupCategory());

PersonUpdateRequestTest: ❌
Response for this Integration Test:

{
  "message": "Forbidden to edit the field statusId",
  "translatedMessage": "Keine Berechtigung um das Feld statusId zu sehen oder zu editieren",
  "messageKey": "error.forbidden.edit.field",
  "args": {
    "field": "statusId"
  },
  "errors": []
}

Error will be fixed in #108