Performance - IL generated content models

Description

Content models are now backed by custom IL generated code handled by the Episerver framework, instead of using Castle proxies. Property access on typed model now have near native performance when accessing a property and zero memory allocation.

The new model does not support ContentDataInterceptor which was an undocumented extension to Castle, so when an interceptor is registered by partner code the framework will automatically fallback to the old slower proxies.