SQL Server container improvements regarding licensing

From how I understand SQL Server's docker container licensing, there are two things that need to be provided to the docker image:

• ACCEPT_EULA=Y
• MSSQL_PID=<your_product_id | edition_name> (default: Developer)

The current approach of having to place an image name in a static file is a bit clunky and doesn't cover the above sufficiently

1. I don't want to run SQL Server using a Developer edition license. I prefer the Express Edition. I guess I can use withEnv("MSSQL_PID", "Express") but it would be nice if I had an enum to choose from with API placed directly on MSSQLServerContainer
2. The Db2Container has an acceptLicense() method, which I think would be nicer than this file on the classpath. Especially, because I'd like to run integration tests using different images of SQL Server, but from the same Maven project, so I cannot easily reuse this file without a build preprocessing step that writes the image name into the file prior to starting the integration tests.

See:
https://hub.docker.com/_/microsoft-mssql-server#environment-variables

Start by inspecting MSSQLServerContainer and Db2Container, then find the current classpath-based image and license configuration and its integration tests. The work is done when SQL Server users can select the product edition and accept the license through the container API without relying on the static file, with tests covering the new behavior.