`marketplace offer package` - support multiple security contexts

## Problem
The user who is interacting with the Partner Center may not be the same security context (service principal) as the current user.

Currently, the active user session (the active access token used from `az login`) is passed into the container in order to perform the work interacting with the ACR instance that's defined in the `manifest.yaml` file.

## Solution
Support passing service principal information into the command, then executing commands inside the docker container to sign in that service principal as the active security context for executing the CPA tool.

Trace the `marketplace offer package` command from its CLI entry point through the Docker container invocation, and inspect how the active `az login` context and the ACR named in `manifest.yaml` are used. Determine how service-principal information should be passed and signed in within the container; done means both user and service-principal contexts can execute the CPA tool against ACR.

Written by the indexing model from the issue text.