[Security Solution] Implement data source fields diff algorithm

[banderror]

Epics: https://github.com/elastic/security-team/issues/1974 (internal), https://github.com/elastic/kibana/issues/174168

Summary

Implement an algorithm for diffing and merging changes in RuleDataSource. It should be applied to:

https://github.com/elastic/kibana/blob/1040bae64087e2d8fb6a4ef77b93b731b74b8d27/x-pack/plugins/security_solution/common/api/detection_engine/prebuilt_rules/model/diff/diffable_rule/diffable_rule.ts#L122

https://github.com/elastic/kibana/blob/1040bae64087e2d8fb6a4ef77b93b731b74b8d27/x-pack/plugins/security_solution/common/api/detection_engine/prebuilt_rules/model/diff/diffable_rule/diffable_rule.ts#L134

https://github.com/elastic/kibana/blob/1040bae64087e2d8fb6a4ef77b93b731b74b8d27/x-pack/plugins/security_solution/common/api/detection_engine/prebuilt_rules/model/diff/diffable_rule/diffable_rule.ts#L146

https://github.com/elastic/kibana/blob/1040bae64087e2d8fb6a4ef77b93b731b74b8d27/x-pack/plugins/security_solution/common/api/detection_engine/prebuilt_rules/model/diff/diffable_rule/diffable_rule.ts#L174

https://github.com/elastic/kibana/blob/1040bae64087e2d8fb6a4ef77b93b731b74b8d27/x-pack/plugins/security_solution/common/api/detection_engine/prebuilt_rules/model/diff/diffable_rule/diffable_rule.ts#L189

https://github.com/elastic/kibana/blob/1040bae64087e2d8fb6a4ef77b93b731b74b8d27/x-pack/plugins/security_solution/common/api/detection_engine/prebuilt_rules/model/diff/diffable_rule/diffable_rule.ts#L212

Context from the Rule Customization RFC:

• Concrete field diff algorithms by type

To do

• [x] Step 1 (separate PR)
  • [x] Implement the algorithm and cover it with unit tests: https://github.com/elastic/kibana/pull/188874
• [x] Step 2 (separate PR)
  • [x] Apply the algorithm to the corresponding rule fields. It will become used in the upgrade/_review endpoint.
  • [x] Write a test plan covering rule upgrade scenarios for the fields to which the algorithm has been applied.
  • [x] https://github.com/elastic/kibana/pull/189669
  • [x] Add test coverage according to the test plan (integration tests, primarily?).
  • [x] https://github.com/elastic/kibana/pull/189744

[elasticmachine]

Pinging @elastic/security-detections-response (Team:Detections and Resp)

[elasticmachine]

Pinging @elastic/security-detection-rule-management (Team:Detection Rule Management)

[elasticmachine]

Pinging @elastic/security-solution (Team: SecuritySolution)

[dplumlee]

Completed by:

• https://github.com/elastic/kibana/pull/188874
• https://github.com/elastic/kibana/pull/189669
• https://github.com/elastic/kibana/pull/189744