Figure out package keys for mittwaldv2/generated/clients and mittwaldv2/generated/schemas

[martin-helmich]

Currently, the schemas in the v2 schema are prefixed with a de.mittwald.v1 key for historical reasons, which translates into package keys like projectsv1. OTOH, the client-specific types are translated into packages keys like projects. This means, in most cases, you'll always have mittwaldv2, projectv1 and project imported, which may get confusing.

Idea:

• mittwaldv2 for the general, top-level client package
• mittwaldv2_project for the resource-specific client package
• schemasv2_project for the schema package (using the API version v2, and ignoring the schema version v1, because no one cares about that)