Commands improvements

[sforward]

Summary

Three improvements to the generator commands:

• Register all commands at once, preventing extra method calls
• Add AsCommand attribute to all commands, so they are not all instantiated on every artisan command execution
• Add return types (breaking change)

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Type of change:

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update
• Misc. change (internal, infrastructure, maintenance, etc.)

Checklist:

• Existing tests have been adapted and/or new tests have been added
• Add a CHANGELOG.md entry
• Update the README.md
• Code style has been fixed via composer fix-style

[mfn]

LGTM, can you please add a changelog entry for the breaking change?

Even if minor, who knows if someone extended one of those commands…

[mfn]

LGTM, thank you!