[CECO-1763] Controller for generic custom resource

[tbavelier]

What does this PR do?

Introduces a generic controller relying on Datadog Go client to handle CRUD operations on multiple resources. Initial support includes notebooks and synthetics (api/browser tests).
Examples:

apiVersion: datadoghq.com/v1alpha1
kind: DatadogGenericCR
metadata:
  name: api-test
spec:
    type: synthetics_api_test
    jsonSpec: |-
        {
           [...]
        }

apiVersion: datadoghq.com/v1alpha1
kind: DatadogGenericCR
metadata:
  name: notebook
spec:
    type: notebook
    jsonSpec: |-
        {
           [...]
        }

Additional Notes

Next steps:

• Document fully-fledged examples
• Document onboarding strategy (e.g. export current resource from the API, create the associated YAML, deploy them)
• Document internally how to add new resources
• UI button to export to manifest
• Add option to start the controller in the Helm chart

Minimum Agent Versions

Are there minimum versions of the Datadog Agent and/or Cluster Agent required?

• Agent: vX.Y.Z
• Cluster Agent: vX.Y.Z

Describe your test plan

1. Include -datadogGenericCREnabled=true in args for the manager container to enable the controller
2. Deploy examples
3. Update their jsonSpec
4. Ensure the changes are reflected in the UI
5. Delete the resources
6. Ensure they are removed from the UI

Checklist

• PR has at least one valid label: bug, enhancement, refactoring, documentation, tooling, and/or dependencies
• PR has a milestone or the qa/skip-qa label

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 40.28926% with 289 lines in your changes missing coverage. Please review.

Project coverage is 48.46%. Comparing base (6ff015c) to head (1f9164f).

Files with missing lines	Patch %	Lines
internal/controller/datadoggenericcr/controller.go	38.97%	74 Missing and 9 partials ⚠️
internal/controller/datadoggenericcr/utils.go	57.05%	67 Missing ⚠️
internal/controller/datadoggenericcr/synthetics.go	0.00%	48 Missing ⚠️
internal/controller/datadoggenericcr/notebooks.go	17.02%	39 Missing ⚠️
internal/controller/datadoggenericcr_controller.go	0.00%	15 Missing ⚠️
pkg/datadogclient/client.go	0.00%	14 Missing ⚠️
internal/controller/setup.go	31.25%	11 Missing ⚠️
internal/controller/datadoggenericcr/finalizer.go	74.35%	7 Missing and 3 partials ⚠️
cmd/main.go	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1534      +/-   ##
==========================================
- Coverage   48.66%   48.46%   -0.20%     
==========================================
  Files         226      234       +8     
  Lines       20363    20847     +484     
==========================================
+ Hits         9909    10104     +195     
- Misses       9937    10214     +277     
- Partials      517      529      +12     

Flag	Coverage Δ
unittests	48.46% <40.28%> (-0.20%)	⬇️

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

Files with missing lines	Coverage Δ
api/datadoghq/v1alpha1/datadoggenericcr_types.go	100.00% <100.00%> (ø)
.../datadoghq/v1alpha1/datadoggenericcr_validation.go	100.00% <100.00%> (ø)
cmd/main.go	0.00% <0.00%> (ø)
internal/controller/datadoggenericcr/finalizer.go	74.35% <74.35%> (ø)
internal/controller/setup.go	49.66% <31.25%> (-2.19%)	⬇️
pkg/datadogclient/client.go	0.00% <0.00%> (ø)
internal/controller/datadoggenericcr_controller.go	0.00% <0.00%> (ø)
internal/controller/datadoggenericcr/notebooks.go	17.02% <17.02%> (ø)
internal/controller/datadoggenericcr/synthetics.go	0.00% <0.00%> (ø)
internal/controller/datadoggenericcr/utils.go	57.05% <57.05%> (ø)
... and 1 more

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