Integrated Alerting: Easier-to-read rule details in Alert Rules list (API to expose Alert Rule's expression and real values)

User story:
When I go to the Alert Rules page I need to see a "final expression" we using in this Alert Rule so the user will have a clear understanding of the technical details for this Alert Rule.

UI/UX:

Acceptance criteria

• Instead of yaml for Alert rule - user can see expression with the values

Out of scope:

Suggested implementation:
1. Add `expr` field to API Rule message
2.  In List request, for each rule execute template with rule params and assign it to rule.

How to test:
Check if route `v1/management/ia/Rules/List` includes `expr` field with final expression

Details:

Return prometheus alert rule yaml content as part of the Alert Rules List request. Right now we can only see the yaml content for the template but as part of PMM-7065 the prometheus alert rule needs to be shown as well to provide more details about the rules.