test: add tests validating use of ROWOFFSET/ROWPARTITION user columns

[Sullivan-Patrick]

Description

Adds testing to ensure ROWOFFSET and ROWPARTITION can freely be used as user columns before KLIP-50 is integrated.

Testing done

Individual tests for ROWOFFSET and ROWPARTITION

Reviewer checklist

• Ensure docs are updated if necessary. (eg. if a user visible feature is being added or changed).
• Ensure relevant issues are linked (description should include text like "Fixes #")

[ghost]

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clabot

[vcrfxia]

Thanks @Sullivan-Patrick . The new tests you've added validate that the names ROWPARTITION and ROWOFFSET may be used as output column aliases, but we also need tests validating that they can be used in source schemas as well.

Also, I think it's fine to just have a single test covering the use of both aliases (minor optimization in order to reduce the number of new tests being added, since we don't expect the behavior for the two aliases to be different).

It might also be interesting to add a test where the new columns have the same data types as the pseudocolumns that will be added as part of KLIP-50.

I've also updated the PR title to reflect that this is a test-only change.

[vcrfxia]

Hey @Sullivan-Patrick thanks for the updates. It looks like we're still missing tests for source columns named ROWPARTITION/ROWOFFSET, though. Both tests are currently testing the use of those names as output column aliases only.

[vcrfxia]

We don't want to have to change the test name once KLIP-50 is implemented (we'd have to remember to rename the historic plan files if so).

Suggested change

	"name": "test ROWOFFSET and ROWPARTITION user columns with data types the pseudocolumns will later represent",
	"name": "test ROWOFFSET and ROWPARTITION user columns with pseudocolumn data types",

[Sullivan-Patrick]

Woops, I totally missed the source schema thing the first time around. Hopefully the latest commits address everything.

[vcrfxia]

Thanks @Sullivan-Patrick -- LGTM!