dev/dn: add ServicesPerPullRequest and ManifestRevision

Created by: bobheadxi

Adds detailed metadata to DeploymentReport require to enable https://github.com/sourcegraph/sourcegraph/pull/33120 , primarily ServicesPerPullRequest, which is an accurate representation of exactly which pull requests are associated with each service in the deployment, because each service might be deployed with a different source diff. This is important for notifications, tracing, etc, and the information is currrently discarded by the report's PRs and services summary.

Test plan

Adds a unit test check, and existing tests should pass.