Refactor the `EvaluationEnvironment` to support dynamic policy updates (hot-reload)

[fabriziosestito]

Description

Refactor the EvaluationEnvironment to support dynamic policy updates.

References

• https://github.com/kubewarden/rfc/blob/main/rfc/0022-policy-lifecycle.md#hot-reload

Acceptance Criteria

• Implement methods to set, update, and remove policies without restart
• Validate policies before loading
• Support multiple versions of the same policy simultaneously

[fabriziosestito]

Please take a look to the POC here: https://github.com/fabriziosestito/policy-server/blob/6e84438717f2f58e71cba685bb64b2a77a3209ec/src/evaluation/evaluation_environment.rs#L67