Enable extensibility provider developers to specify diagnostic rules as part of provider definition

**Is your feature request related to a problem? Please describe.**
Current implementation of Bicep doesn't allow extensibility providers to declare linting rules on the types that they define. This results in a degraded ability to relay constraints about the resource modeling to the author of the Bicep manifest.

Start by tracing how extensibility provider definitions are represented and how diagnostic or linting rules are currently processed. The work is done when provider developers can declare rules for their defined types and those constraints are relayed to authors of Bicep manifests.

Written by the indexing model from the issue text.