Support private-only container for BYO credentials

### Expected Behaviour

Users should be able to set init with a `noPublic` option.
OR by default, we should only create a private container and add a `addPublic` option (breaking change)

### Actual Behaviour

Init will create a private and a public container, this doesn't work for users that need to keep their azure instance private

Start at the library's init entry point and trace how it creates the private and public containers. Implement the selected noPublic or addPublic behavior so users can keep the Azure instance private, then verify the initialization behavior with the project's existing tests.

Written by the indexing model from the issue text.