[#2758] Add the KlantContact and related resources to the openklant2 client

[swrichards]

All this is part of Taiga 2681.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 74.37888% with 165 lines in your changes missing coverage. Please review.

Project coverage is 94.52%. Comparing base (f081910) to head (37d3c3a).

Files with missing lines	Patch %	Lines
src/openklant2/tests/test_betrokkene.py	46.15%	35 Missing ⚠️
src/openklant2/tests/test_onderwerp_object.py	45.45%	24 Missing ⚠️
src/openklant2/tests/test_actor.py	47.61%	22 Missing ⚠️
src/openklant2/tests/test_klant_contact.py	47.50%	21 Missing ⚠️
src/openklant2/tests/test_interne_taak.py	52.50%	19 Missing ⚠️
src/openklant2/_resources/base.py	41.66%	14 Missing ⚠️
src/openklant2/_resources/actor.py	66.66%	6 Missing ⚠️
src/openklant2/_resources/betrokkene.py	71.42%	6 Missing ⚠️
src/openklant2/_resources/interne_taak.py	71.42%	6 Missing ⚠️
src/openklant2/_resources/klant_contact.py	71.42%	6 Missing ⚠️
... and 1 more

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #1404      +/-   ##
===========================================
- Coverage    94.85%   94.52%   -0.34%     
===========================================
  Files         1049     1069      +20     
  Lines        38845    39487     +642     
===========================================
+ Hits         36848    37325     +477     
- Misses        1997     2162     +165     

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