Remove init function and types from the final output

The pre-initialization process currently involves an exported anonymous interface and types (defined in init.wit). That should be stripped out of the final component since it's not part of the application's world.

Start with init.wit and trace the pre-initialization process to where the final component is produced. Verify that the exported anonymous interface and related types are absent from the final component while the application's world remains intact. The issue does not name a test, so identify the relevant existing component-generation checks before making changes.

Written by the indexing model from the issue text.