MCP registry endpoint check

When a user is registering an MCP server via `opsmlspec.yml`, we should check to ensure at least one `deploy` config with an endpoint as been provided. Registering without an endpoint is pointless considering the goal of the MCP registry is allow other users to discover and use MCP servers from the registry

Start by locating the validation and registration path for opsmlspec.yml. Check how deploy configurations and endpoints are represented, then make registration require at least one deploy config with an endpoint. Done means configurations without an endpoint are rejected while valid MCP server registrations continue to work.

Written by the indexing model from the issue text.