feat: add generated command shortcuts

[Alexander Jank (jankal)]

Summary

• add automatic shortcut aliases for cobra commands based on unique prefixes
• support nested command paths like shopware-cli p e l
• cover top-level, nested, and commands that already define aliases with tests

Testing

• unable to run locally in this environment because the host does not currently have Go/gofmt installed
• GitHub Actions should validate build and tests on the PR