Move generated assets into separate folder inside the public folder

[tom2drum]

Description and Related Issue(s)

Resolves #1898

Added build-time ENV NEXT_OPEN_TELEMETRY_ENABLED to explicitly enable OpenTelemetry for a docker image.

Checklist for PR author

• [x] I have tested these changes locally.
• [x] I added tests to cover any new functionality, following this guide
• [x] Whenever I fix a bug, I include a regression test to ensure that the bug does not reappear silently.
• [x] If I have added, changed, renamed, or removed an environment variable, I have updated the list of environment variables in the documentation and made the necessary changes to the validator script according to the guide