Sdk resolution should emit some events to help with debugging

On diagnostic verbosity:
- at the start of each evaluation (or maybe at the start of the build, to have it only once) log the resolver chain in order
- whenever the Evaluator asks the SdkResolverService for an sdk, it should emit an event stating:
- referenced sdk
- actual sdk resolved (actual version)
- sdk path
- resolver that resolved it (type simple name and assembly path). Also mention whether it resolved from the cache or not