Allow to specify `DockerImageName` in addition to simple string

[lbroudoux]

Reason/Context

As of today, some containers can only be instantiated, providing image coordinates.

Description

Providing DockerImageName allows to force compatibility mode and provides better flexibility for users.

Implementation ideas

New constructors and with() methods must be added on MicrocksContainersEnsemble

[lbroudoux]

Now done.