collectEvents at Cluster Agent level

[carloscastrojumo]

What does this PR do?

Add the property collectEvents at clusterAgent config to enable setting DD_COLLECT_KUBERNETES_EVENTS env var.

Motivation

Collecting Kubernetes events using the Cluster Agent instead of Node Agents.

Additional Notes

Based on the Event Collection documentation for Cluster Agent.

[codecov-commenter]

Codecov Report

Merging #154 into master will decrease coverage by 0.77%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #154      +/-   ##
==========================================
- Coverage   59.02%   58.24%   -0.78%     
==========================================
  Files          31       31              
  Lines        4961     4514     -447     
==========================================
- Hits         2928     2629     -299     
+ Misses       1817     1680     -137     
+ Partials      216      205      -11     

Flag	Coverage Δ
#unittests	58.24% <100.00%> (-0.78%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
pkg/controller/datadogagent/clusteragent.go	68.79% <100.00%> (-1.16%)	⬇️
pkg/secrets/utils.go	85.71% <0.00%> (-4.29%)	⬇️
pkg/controller/datadogagent/finalizer.go	34.78% <0.00%> (-3.68%)	⬇️
pkg/controller/datadogagent/common_configmap.go	59.74% <0.00%> (-2.62%)	⬇️
pkg/controller/datadogagent/secret.go	54.54% <0.00%> (-2.60%)	⬇️
cmd/kubectl-datadog/flare/replacer.go	85.96% <0.00%> (-2.45%)	⬇️
pkg/controller/datadogagent/common_rbac.go	73.86% <0.00%> (-2.43%)	⬇️
...ontroller/datadogagent/clusterchecksrunner_rbac.go	70.37% <0.00%> (-2.05%)	⬇️
pkg/controller/utils/datadog/metrics_forwarder.go	40.46% <0.00%> (-2.01%)	⬇️
pkg/controller/datadogagent/service.go	80.88% <0.00%> (-1.98%)	⬇️
... and 22 more

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[ahmed-mez]

Thanks for the contribution