fix: feature update api not validating required fields before saving

[cre8ivejp]

Part of #893

Things done

• Fixed feature update API replacing fields without validating them
• Implemented granular changes for the scheduled change feature

---

This pull request includes significant updates to the api-description YAML files and various Go files to support new feature change types and granular change operations. The most important changes are grouped into updates to the API descriptions and updates to the Go codebase.

Updates to API descriptions:

• Added descriptions for deprecated fields and introduced new fields such as resetSamplingSeed, variationChanges, ruleChanges, prerequisiteChanges, targetChanges, and tagChanges in api-description/apidocs.swagger.yaml.
• Introduced a new featureChangeType enumeration to specify the type of changes (e.g., CREATE, UPDATE, DELETE) in api-description/apidocs.swagger.yaml and api-description/web-api.swagger.yaml. [1] [2]
• Added new object definitions for featurePrerequisiteChange, featureRuleChange, featureTagChange, featureTargetChange, and featureVariationChange in api-description/apidocs.swagger.yaml and api-description/web-api.swagger.yaml. [1] [2]

Updates to Go codebase:

• Updated the ExecuteProgressiveRollout method in pkg/autoops/api/progressive_rollout.go and the UpdateFeature method in pkg/feature/api/feature.go to handle new change types and fields. [1] [2]
• Added new error definitions and validation logic for rules, variations, and prerequisites in pkg/feature/domain/feature.go. [1] [2] [3]
• Introduced new methods for changing and removing rules and variations, and validating prerequisites in pkg/feature/domain/feature.go. [1] [2] [3]

[hvn2k1]

Thank you!

[Ubisoft-potato]

Great work! 👍