[Security Solution] Implement rule type diff algorithm

[xcrzx]

Epics: https://github.com/elastic/security-team/issues/1974 (internal), https://github.com/elastic/kibana/issues/174168 Related to: https://github.com/elastic/kibana/issues/180395

Summary

Implement an algorithm for diffing the type field of detection rules. Requirements:

• The algorithm should always return the target version as the merged one.
• Any change to the rule type (i.e. current version != target version) should yield an unsolvable conflict.
• In the upgrade/_review API response such rules should be marked as having unsolvable conflicts.
• Users should not be able to upgrade the type to any version other than the target. This should be implemented under the hood in the upgrade/_perform endpoint in https://github.com/elastic/kibana/issues/166376. The type field shouldn't be part of upgradeable fields that can be passed in the request body -- FYI @jpdjere

Context from the Rule Customization RFC:

• Concrete field diff algorithms by type

To do

• [ ] Step 1 (separate PR)
  • [ ] Implement the algorithm and cover it with unit tests
• [ ] Step 2 (separate PR)
  • [ ] Apply the algorithm to the type field. It will become used in the upgrade/_review endpoint.
  • [ ] Write a test plan covering rule upgrade scenarios for rule type updates.
  • [ ] Add test coverage according to the test plan.

[elasticmachine]

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

[elasticmachine]

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

[elasticmachine]

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