Add reservoir_sample aggregation function

[ZacBlanco]

Description

This commit introduces a new reservoir_sample aggregate function which, as opposed to the existing TABLESAMPLE operator lets users pick a fixed sample size.

The fixed sample sizes lets users create samples of a known total size while guaranteeing every record has an equal probability of being chosen.

Motivation and Context

Useful for generating fixed-size samples

Impact

New reservoir_sample aggregation function.

Test Plan

Unit tests for the function are included.

Contributor checklist

• Please make sure your submission complies with our development, formatting, commit message, and attribution guidelines.
• PR description addresses the issue accurately and concisely. If the change is non-trivial, a GitHub Issue is referenced.
• Documented new properties (with its default value), SQL syntax, functions, or other functionality.
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• Adequate tests were added if applicable.
• CI passed.

Release Notes

== RELEASE NOTES ==

General Changes
* A reservoir_sample aggregation function is now available

[github-actions]

Codenotify: Notifying subscribers in CODENOTIFY files for diff 24aec09...6f47a4c.

Notify	File(s)
@steveburnett	presto-docs/src/main/sphinx/functions/aggregate.rst presto-docs/src/main/sphinx/sql/select.rst

[steveburnett]

Thanks for the doc! I made some suggestions for conciseness and readability. As always, if my suggestions change your intended meaning in a way that doesn't accurately represent your intended meaning, let me know and I'm happy to discuss.

[steveburnett]

LGTM! (docs)

Tested latest changes in a new local build, the docs look fine. Thanks!

[steveburnett]

Two small nits rechecking the doc in a new local build.

[ZacBlanco]

@ClarenceThreepwood FYI..found the cause of the issue I was having earlier. I needed the function to be called on null inputs, but isCalledOnNullInput in the function header doesn't automatically fix it.

I have to put the undocumented @NullablePosition annotation alongside the nullable parameters as well to get the input function to be called

[steveburnett]

LGTM! (docs)

[aaneja]

Can you add a pointer in the docs or as a code comment on what the error message would be if a very large sample would need to cross an exchange boundary. IIRC it was the same error as any other non-scalar type that doesn't fit a max-width limit we have for non-scalars ?

[steveburnett]

I like the additions! I've suggested some minor punctuation and phrasing changes for you to consider.

[steveburnett]

LGTM! (docs)

New local build, everything looks great. Thanks!