Integrate convert tool (tsp-openapi3) into vscode

[RodgeFu]

Clear and concise description of the problem

User should be able to import from openapi to typespec easily in vscode

Checklist

• [x] Follow our Code of Conduct
• [x] Read the docs.
• [x] Check that there isn't already an issue that request the same feature to avoid creating a duplicate.

[josefree]

what's current OpenApi 3.0 version we support to convert？

[RodgeFu]

I think that would depends what version the tool supports, isn't it?