Add sli_aggregations recording rules in mimir-rules

For gitlab-com/gl-infra/scalability#2602 (closed)

In this MR:

• Generates the SLI aggregations recording rules, aka the first layer of recording rule for the SLIs defined per service. This also includes scoping the rules by env and type selector
• Add emittedBy field in the SLI definition to keep track of which SLIs are emitted by other services. By default, the emittedBy field is the service itself.