♻️ refactor(mq-lang): extract DateUnit enum for date built-ins

[harehare]

No description provided.

[codspeed-hq]

Merging this PR will not alter performance

✅ 29 untouched benchmarks

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_{Comparing refactor/date-unit-enum (bfff8e5) with main (3a611d4)¹}

Footnotes

1. No successful run was found on main (ecd0979) during the generation of this report, so 3a611d4 was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩