drop BaseService from MemberClusterService & use Client directly

[MatousJobanek]

• drops BaseService from MemberClusterService
• uses the controller-runtime client directly for communication with k8s api
• the implementation of the SignupService is set directly (not via the BaseService) which simplifies the tests

this is a prerequisite for dropping the InformerService KUBESAW-198

[codecov]

Codecov Report

Attention: Patch coverage is 90.00000% with 1 line in your changes missing coverage. Please review.

Project coverage is 85.43%. Comparing base (fb4418b) to head (1713c85).
Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
pkg/proxy/service/cluster_service.go	88.88%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #477      +/-   ##
==========================================
- Coverage   85.45%   85.43%   -0.03%     
==========================================
  Files          33       33              
  Lines        2523     2519       -4     
==========================================
- Hits         2156     2152       -4     
  Misses        281      281              
  Partials       86       86              

Flag	Coverage Δ
unittests	85.43% <90.00%> (-0.03%)	⬇️

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[sonarcloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud

[mfrancisc]

Nice 👍

[openshift-ci]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: alexeykazakov, MatousJobanek, mfrancisc

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