[Draft]Add SQL logic tests for Run-End Encoded (REE)

[rich-t-kid-datadog]

This PR contributes towards the larger (RLE)/(REE) epic!

Rationale for this change

DataFusion currently supports REE encoding through Arrow's RunEndEncoded type, but lacks comprehensive testing to ensure this functionality works correctly across various SQL operations.
This PR adds comprehensive test coverage for REE-encoded data to ensure that:

• Basic SQL operations (filtering, selection, aggregation) work correctly with REE columns
• String functions (LOWER, UPPER, CONCAT, SUBSTR, REPLACE, REVERSE) properly handle REE-encoded data
• Complex queries involving multiple REE columns function as expected
• The encoding/decoding process is transparent to users and maintains data integrity

What changes are included in this PR?

This PR adds a new test file run_end_encoding.slt that provides comprehensive testing for Run-End Encoded data:

1. Basic REE Functionality

• Table creation with REE-encoded columns using arrow_cast(column, 'RunEndEncoded(Int32, Utf8)')
• Verification of correct data types via DESCRIBE statements

2. Filtering and Selection

• Filtering on REE columns
• Combined filtering on REE and non-REE columns

3. Aggregation Functions

• COUNT(*) and COUNT(DISTINCT) on REE columns

4. String Function Testing

• LOWER() and UPPER() on REE columns
• CONCAT() with REE columns (including nested operations)
• SUBSTR()/SUBSTRING() on REE columns
• REPLACE() on REE columns
• REVERSE() on REE columns
• Combined string functions (e.g., UPPER(SUBSTR(...)))

Are these changes tested?

The changes are test.

Are there any user-facing changes?

As of now, no. A majority of these test wont pass as of now due to the lack of support but it gives a guideline as to what our focus is.

[rich-t-kid-datadog]

TODO: Add Hash Joins
Not a priority

[fmonjalet]

For these tests it could be nice to have a way to verify the output type is also Run End Encoded (as opposed to DataFusion implicitly casting to Utf8)

[gabotechs]

Looking good! how about adding some test that try to stress REE with some more edge cases, for example, we could have tests that check for REE input containing NULLs, or when the input table contains no duplicates