Move `builder` folder out of `src`

In early design builder was a core component to be consumed by the end users, but now it is only used to create a service worker for e2e tests.

Its better to move it out of `src` directory.

Inspect the src/builder directory and search for its references in the end-to-end test setup. Identify a non-src location for the builder while preserving service-worker creation for e2e tests. Done means the builder is no longer under src and the existing e2e service-worker workflow still works.

Written by the indexing model from the issue text.