minor: Refactor schema type checking logic for scans

[andygrove]

Which issue does this PR close?

Closes #.

Rationale for this change

I would like auto mode to start supporting native_datafusion, but I want to refactor the current code first.

What changes are included in this PR?

• Move schema type checks into CometNativeScan and CometIcebergNativeScan
• ...
• Add new tests

How are these changes tested?

[codecov-commenter]

Codecov Report

❌ Patch coverage is 70.00000% with 12 lines in your changes missing coverage. Please review.
✅ Project coverage is 59.67%. Comparing base (f09f8af) to head (1c81264).
⚠️ Report is 782 commits behind head on main.

Files with missing lines	Patch %	Lines
...n/scala/org/apache/comet/rules/CometScanRule.scala	71.42%	0 Missing and 4 partials ⚠️
.../apache/comet/serde/operator/CometNativeScan.scala	50.00%	3 Missing and 1 partial ⚠️
.../main/scala/org/apache/comet/DataTypeSupport.scala	33.33%	1 Missing and 1 partial ⚠️
.../comet/serde/operator/CometIcebergNativeScan.scala	86.66%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #2942      +/-   ##
============================================
+ Coverage     56.12%   59.67%   +3.54%     
- Complexity      976     1373     +397     
============================================
  Files           119      167      +48     
  Lines         11743    15462    +3719     
  Branches       2251     2557     +306     
============================================
+ Hits           6591     9227    +2636     
- Misses         4012     4944     +932     
- Partials       1140     1291     +151     

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