A SlotRenderingProvider is an object that provides access to ParserOutput (or Rendering) objects for each slot. That is, it has an interface exposign a method like this:
- getSlotRendering( $role ): ParserOutput.
We need an implementation of SlotRenderingProvider that provides in-place caching of the ParserOutput, as well as on-demand (lazy) generation of the ParserOutput (with the option to generate only meta-data and no HTML).