This is the OSS portion of enterprise PR 2460.
Introduces a server-local implementation of the proxycfg.ResolvedServiceConfig
interface that sources data from a blocking query against the server's state
store.
It moves the service config resolution logic into the agent/configentry package
so that it can be used in both the RPC handler and data source.
I've also done a little re-arranging and adding comments to call out data
sources for which there is to be no server-local equivalent.
Adds a new query param merge-central-config for use with the below endpoints:
/catalog/service/:service
/catalog/connect/:service
/health/service/:service
/health/connect/:service
If set on the request, the response will include a fully resolved service definition which is merged with the proxy-defaults/global and service-defaults/:service config entries (on-demand style). This is useful to view the full service definition for a mesh service (connect-proxy kind or gateway kind) which might not be merged before being written into the catalog (example: in case of services in the agentless model).
