feat(metrics-operator): add support for user-friendly duration string for specifying time frame

[bacherfl]

Closes #2129

This PR adds the feature described in #2129. The name of the new property is spec.timeframe.recent and it accepts a duration string as an input. As the name suggests, if this property is set to a value x, the timeframe for the analysis will be between now() - x and now(). This timeframe is derived at the first time the Analysis is being reconciled. The derived timestamps are then stored in the status of the Analysis, otherwise the timeframe might shift over the course of multiple reconciliation loops.

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[codecov]

Codecov Report

Merging #2147 (eb005a6) into main (98097e6) will increase coverage by 0.04%.
The diff coverage is 91.95%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2147      +/-   ##
==========================================
+ Coverage   84.52%   84.57%   +0.04%     
==========================================
  Files         152      153       +1     
  Lines        9804     9881      +77     
==========================================
+ Hits         8287     8357      +70     
- Misses       1230     1237       +7     
  Partials      287      287              

Files	Coverage Δ
metrics-operator/api/v1alpha3/analysis_types.go	100.00% <100.00%> (ø)
...etrics-operator/controllers/analysis/controller.go	84.74% <100.00%> (+0.39%)	⬆️
...rator/controllers/analysis/objectives_evaluator.go	77.27% <100.00%> (ø)
...or/controllers/common/providers/datadog/datadog.go	89.36% <100.00%> (ø)
...trollers/common/providers/prometheus/prometheus.go	84.04% <100.00%> (ø)
...-operator/controllers/common/providers/provider.go	100.00% <ø> (ø)
...ollers/common/providers/dynatrace/dynatrace_dql.go	80.75% <0.00%> (ø)
...ontrollers/common/providers/dynatrace/dynatrace.go	83.87% <0.00%> (ø)
metrics-operator/api/v1alpha3/analysis_webhook.go	91.66% <91.66%> (ø)

... and 4 files with indirect coverage changes

Flag	Coverage Δ
certificate-operator	65.91% <ø> (ø)
component-tests	58.65% <ø> (ø)
lifecycle-operator	85.02% <ø> (ø)
metrics-operator	87.50% <91.95%> (+0.09%)	⬆️
scheduler	32.12% <ø> (ø)

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[sonarcloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
1 Code Smell

No Coverage information
0.0% Duplication

[RealAnna]

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