chore: enable use of tsgo preview

[AlCalzone]

Remaining blockers:

• [ ] No decorator downleveling support (worked around in this PR)
• [ ] @validateArgs transformers don't work. Options:
  • Ditch ts-patch and transform in a pre-compile step. Possibly using TypeScript's API wrapper: https://github.com/microsoft/typescript-go/pull/711
  • Wait for API support