U4-10026 - Core/Deploy Perfs issues with GetById(Guid key) methods

PR: https://github.com/umbraco/Umbraco-CMS/pull/2004

instead of doing Get by Guid hitting the DB everytime, we now use the internal id-key cache map that was only in EntityService. should be way faster.

also refactored that cache map so that it's cross-referencing (id to key and key to id) and is generally faster according to benchmarks.

also refactored how that cache map is cleared so that instead of clearing the whole of it every time, we only remove the impacted entries.

review: try to restore a remote site and see if there's a difference.

Added comments to PR, we just need to inject the IdKMap to the services

arh... obviously, but it's kinda a pain because the service ctors are all public and so that would break compat, which is why I haven't done it. Suggestions?

Yes, but we've had this documented for years now: https://our.umbraco.org/Documentation/Development-Guidelines/breaking-changes#non-breaking

People cannot/should not be constructing these services in their website code. In the past we've created new service ctor overloads and obsoleted the old ones - which we can do for this too.

k - fixing today

pushed, up for review

Looks good to me!