feat: Enable native_datafusion scans in auto scan mode [WIP]

[andygrove]

Which issue does this PR close?

Follows on from the refactor in #2978

Rationale for this change

native_datafusion is faster than native_iceberg_compat, so we should use it when we can.

What changes are included in this PR?

How are these changes tested?

[codecov-commenter]

Codecov Report

❌ Patch coverage is 72.72727% with 12 lines in your changes missing coverage. Please review.
✅ Project coverage is 53.94%. Comparing base (f09f8af) to head (d281304).
⚠️ Report is 797 commits behind head on main.

Files with missing lines	Patch %	Lines
...n/scala/org/apache/comet/rules/CometScanRule.scala	72.72%	5 Missing and 7 partials ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #2969      +/-   ##
============================================
- Coverage     56.12%   53.94%   -2.18%     
- Complexity      976     1221     +245     
============================================
  Files           119      167      +48     
  Lines         11743    15515    +3772     
  Branches       2251     2570     +319     
============================================
+ Hits           6591     8370    +1779     
- Misses         4012     5947    +1935     
- Partials       1140     1198      +58     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.