Support nested schema of emitter options for doc generation and cli

Current doc generated for emitter options does not support nested schema. See [example](https://tspwebsitepr.z22.web.core.windows.net/typespec-azure/prs/2393/docs/libraries/typespec-client-generator-core/reference/emitter/#license). `license` could only show up as an object, but it has detailed nested schema defined [here](https://github.com/Azure/typespec-azure/blob/cc97a33c58ac71a02ea084a41be3877617925c67/packages/typespec-client-generator-core/src/lib.ts#L57). Also, it seems we could not pass a nested config with typespec cli.