feat(expr): support IGNORE NULLS for first_value/last_value

[stdrc]

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What's changed and what's your intention?

This PR implements IGNORE NULLS support for first_value and last_value window functions, similar to duckdb.

Syntax:

select
    *,
    first_value(val) over (partition by 1::int order by ts) as first,
    first_value(val ignore nulls) over (partition by 1::int order by ts) as first_non_null,
    first_value(val ignore nulls) over (partition by 1::int order by ts rows between 1 preceding and 1 following) as first_non_null_2,
    last_value(val) over (partition by 1::int order by ts) as last,
    last_value(val ignore nulls) over (partition by 1::int order by ts) as last_non_null,
    last_value(val ignore nulls) over (partition by 1::int order by ts rows between 1 preceding and 1 following) as last_non_null_2
from t;

Fixes #17601.

lag and lead still don't support this syntax due to some historical reason. Will implement for them later.

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.
• My PR contains critical fixes that are necessary to be merged into the latest release.

Documentation

• My PR needs documentation updates.

Release note

• Support IGNORE NULLS for first_value and last_value window functions. Syntax:

  first_value(val IGNORE NULLS) OVER (...)

[stdrc]

• feat(expr): support IGNORE NULLS for first_value/last_value #19847 👈 (View in Graphite)
• main

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[github-actions]

Hi, there.

📝 Telemetry Reminder:
If you're implementing this feature, please consider adding telemetry metrics to track its usage. This helps us understand how the feature is being used and improve it further.
You can find the function report_event of telemetry reporting in the following files. Feel free to ask questions if you need any guidance!

• src/frontend/src/telemetry.rs
• src/meta/src/telemetry.rs
• src/stream/src/telemetry.rs
• src/storage/compactor/src/telemetry.rs
  Or calling report_event_common (src/common/telemetry_event/src/lib.rs) as if finding it hard to implement.
  ✨ Thank you for your contribution to RisingWave! ✨

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