Use webcontainers for code artifacts

[marcusschiesser]

• Add a /sandbox route that uses https://webcontainers.io/ instead of e2b to execute the code (for Python and TS) - the result is that we have two sandbox routes, one for E2B and one for webcontainers
• In the generated code, we only want one route, hence we copy the route as a component. Which route to select depends on the selected tool; for web containers, we add artifact[webcontainers]

Note: Webcontainers only work with generated TS code, but our code generator tool works for Python and TS (so we need to test both).