minor: Add RDDScan to default value of sparkToColumnar.supportedOperatorList

[wForget]

Which issue does this PR close?

Closes #.

Rationale for this change

To make it easier for us to write test cases for comet expressions like #2410.

What changes are included in this PR?

How are these changes tested?

This test case ran successfully:

  test("test array literal") {
    withSQLConf(
      CometConf.COMET_SPARK_TO_ARROW_ENABLED.key -> "true",
      SQLConf.OPTIMIZER_EXCLUDED_RULES.key -> "org.apache.spark.sql.catalyst.optimizer.ConstantFolding") {
      checkSparkAnswerAndOperator("select array('1', '2', '3')")
    }
  }

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 57.84%. Comparing base (f09f8af) to head (a362046).
⚠️ Report is 1166 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #2422      +/-   ##
============================================
+ Coverage     56.12%   57.84%   +1.71%     
- Complexity      976     1401     +425     
============================================
  Files           119      147      +28     
  Lines         11743    13469    +1726     
  Branches       2251     2341      +90     
============================================
+ Hits           6591     7791    +1200     
- Misses         4012     4446     +434     
- Partials       1140     1232      +92     

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[cfmcgrady]

A cheaper approach than the one I took on my dev branch (where I implemented a JVM-based CometOneRowRelation for native OneRowRelation scans).

[andygrove]

Nice. Thanks @wForget

[comphead]

Thanks @wForget
@cfmcgrady do you feel it closes #2410 ?