feat(expr): implement gamma/lgamma function

[Standing-Man]

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What's changed and what's your intention?

• Closes Part of feat(expr): PostgreSQL 18 new expressions #23368.

  • gamma function
  • lgamma function

Checklist

• I have written necessary rustdoc comments.
• I have added necessary unit tests and integration tests.
• I have added test labels as necessary.
• I have added fuzzing tests or opened an issue to track them.
• My PR contains breaking changes.
• My PR changes performance-critical code, so I will run (micro) benchmarks and present the results.
• I have checked the Release Timeline and Currently Supported Versions to determine which release branches I need to cherry-pick this PR into.

Documentation

• My PR needs documentation updates.

Release note

support gamma and lgamma function

[Standing-Man]

Hi @hzxa21, I’m a bit unsure whether the gamma function should be wrapped in the F64.

risingwave/src/common/src/types/ordered_float.rs

Line 812 in ccea659

fn to_radians(self) -> Self {

related issue: rust-lang/rust#99842

[hzxa21]

Hi @hzxa21, I’m a bit unsure whether the gamma function should be wrapped in the F64.

risingwave/src/common/src/types/ordered_float.rs

Line 812 in ccea659

fn to_radians(self) -> Self {

related issue: rust-lang/rust#99842

cc the original author of ordered_float to check @BugenZhao

[BugenZhao]

Rest LGTM. Thanks for contribution!

[Standing-Man]

Hi @xiangjinwu, PTAL when you have time. 😄