[Security Solution] Add support for Fleet package with historical versions of prebuilt rules

[banderror]

Epic: https://github.com/elastic/security-team/issues/1974 (internal)

Summary

Add support for historical rule asset saved objects according to the data model chosen based on #144060. Adjust the code to support both the latest and historical rule assets at the same time, so we could release the security_detection_engine package with historical versions at any given time.

Todo

• Figure out what should we do with existing security-rule saved objects.
• Adjust the existing rules/prepackaged endpoints so that they could be used with both the latest and historical rule assets.

Details

Saved objects

Figure out what should we do with existing security-rule saved objects. Options:

1. Keep existing security-rule saved objects type unchanged. There's a chance we could reuse it for storing historical rule assets without any modifications.
2. Adjust existing security-rule saved objects type according to the needs, so it's capable of storing historical assets.
3. Create a new saved objects type for historical assets.

Options 1 and 2 look more suitable for the flat data model. Option 3 looks more suitable for the composite data model.

Existing endpoints

Adjust the two existing rules/prepackaged endpoints so that they could be used with both the latest and historical rule assets.

The endpoints should determine which assets are stored based on the data in the assets. We could write some aggregation queries for that.

Keep the contract and the existing behavior of the endpoints unchanged regardless of what kind of data is stored under the hood.

[elasticmachine]

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

[elasticmachine]

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