[codegen] add scala 3 keywords to collision avoidance

[jpassaro]

PR Checklist (not all items are relevant to all PRs)

• Added unit-tests (for runtime code)
• Added bootstrapped code + smoke tests (when the rendering logic is modified)
• (N/A) Added build-plugins integration tests (when reflection loading is required at codegen-time)
• (N/A) Added alloy compliance tests (when simpleRestJson protocol behaviour is expanded/updated)
• Updated dynamic module to match generated-code behaviour
• Added documentation
• Updated changelog

[CLAassistant]

All committers have signed the CLA.

[jpassaro]

thanks kindly to @kubukoz and @Baccata for thoughtful feedback and @daddykotex for the changelog. I think I've got it all covered now.

[daddykotex]

Thanks for the PR

[kubukoz]

Thanks @jpassaro :)

[jpassaro]

thanks for the merge and swift release!