[SPARK-51510] Add SQL-file based SQLTests suite

[dongjoon-hyun]

What changes were proposed in this pull request?

This PR aims to add SQL-file based SQLTests suite as a new test framework. For example,

• pipesyntax.sql

VALUES (0), (1) tab(col)
|> EXTEND col * 2 AS result

• pipesyntax.sql.json

[["0","0"],["1","2"]]

Why are the changes needed?

This framework helps us improve test coverage by adding SQL file and golden answer files.

Does this PR introduce any user-facing change?

No.

How was this patch tested?

Manual test against Apache Spark 4.0.0 RC2 and pass the CIs.

$ swift test --filter SQLTests
...
􀟈  Suite SQLTests started.
􀟈  Test runAll() started.
pipesyntax.sql
select.sql
􁁛  Test runAll() passed after 0.083 seconds.
􁁛  Suite SQLTests passed after 0.083 seconds.
􁁛  Test run with 1 test passed after 0.083 seconds.

Was this patch authored or co-authored using generative AI tooling?

No.

[dongjoon-hyun]

Could you review this test framework PR when you have some time, @LuciferYang ?

[LuciferYang]

+1, LGTM

[dongjoon-hyun]

Thank you, @LuciferYang !

[dongjoon-hyun]

Merged to main.