Create tool that can scaffold a resource based on an HCL file/snippet

### Proposal

It would be nice if there were a cmd line tool that could help in writing / scaffolding provider code (similar to `rails generate`, etc). It would be cool if you could start with your UX/HCL and have the schema/code stubbed out automatically.

The proposal names no files, tests, or entry points. Start by locating the SDK's provider and resource-generation code and command-line entry points, then clarify the HCL input, generated schema or code scope, and completion criteria with maintainers.

Written by the indexing model from the issue text.