Provide a migration path or explicit support for devcontainers #1132

To continue an idea I had in #928

Most people today are using devcontainers with VSCode. Having easy compatibility or a clear migration path from devcontainers to workshops could really help uptake.

• A migration path might include a tool to convert devcontainer config files into workshop config files. Another approach is to create an agent skill explaining to an agent how to do that migration.
• Explicit support or explicit compatibility would mean that workshop can simply use the existing devcontainer config, and wrap the devcontainer inside of a workshop.