## Summary

This PR implements the `forwardCompatibility` field for the rule model
version in preparation for the flapping PR
(elastic#190019). We're doing this so we
have the point to revert back to if we need to where the
`forwardCompatibility` is defined.

---------

Co-authored-by: kibanamachine <42973632+kibanamachine@users.noreply.github.com>
(cherry picked from commit bb18996)

… (#193695)

# Backport

This will backport the following commits from `main` to `8.x`:
- [[Response Ops][Rules] Rule Model Version Forward Compat
(#193233)](#193233)

<!--- Backport version: 9.4.3 -->

### Questions ?
Please refer to the [Backport tool
documentation](https://github.com/sqren/backport)

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so we\r\nhave the point to revert back to if we need to where
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Co-authored-by: Jiawei Wu <74562234+JiaweiWu@users.noreply.github.com>