Install generator only if needed

[florian-richter]

Proposed Changes

The CLI can currently not be installed unless the @SAP:registry is configured as the generator is a necessary dependency. This removes the dependency and installs the generator globally if needed.

Checklist

• I have added or adjusted tests that prove my fix is effective or that my feature works
• I have added or adjusted documentation

[mr-flannery]

As discussed, as a temporary fix this should be okay. Maybe make more explicit what's happening when you ask whether the generator should be installed globally.