fix: support parquet floating point columns as varchar

[guhaiyan0221]

Allow REAL and DOUBLE Parquet columns to be read as VARCHAR. For ordinary Hive Parquet splits, reject incompatible VARCHAR value filters before they reach floating-point readers. When only metadata pruning is involved, disable the metadata filter and evaluate the residual predicate after conversion. Keep IS NULL and IS NOT NULL pushdown unchanged, and exclude Paimon splits from this handling.

What problem does this PR solve?

Issue Number: close #796

Type of Change

• 🐛 Bug fix (non-breaking change which fixes an issue)
• ✨ New feature (non-breaking change which adds functionality)
• 🚀 Performance improvement (optimization)
• ⚠️ Breaking change (fix or feature that would cause existing functionality to change)
• 🔨 Refactoring (no logic changes)
• 🔧 Build/CI or Infrastructure changes
• 📝 Documentation only

Description

• Support reading Parquet FLOAT and DOUBLE columns as VARCHAR.
• Reject incompatible VARCHAR value filters before they reach floating-point readers.
• Skip incompatible metadata-filter leaves while preserving null checks and compatible row-group pruning.
• Cover scalar, filter-only, nested map, and metadata-filter scenarios.

Performance Impact

• No Impact: This change does not affect the critical path (e.g., build system, doc, error handling).

• Positive Impact: I have run benchmarks.

  Click to view Benchmark Results

  Paste your google-benchmark or TPC-H results here.
  Before: 10.5s
  After:   8.2s  (+20%)
  

• Negative Impact: Explained below (e.g., trade-off for correctness).

Release Note

Please describe the changes in this PR

Release Note:

Release Note:
- fix: support parquet floating point columns as varchar

Checklist (For Author)

• I have added/updated unit tests (ctest).
• I have verified the code with local build (Release/Debug).
• I have run clang-format / linters.
• (Optional) I have run Sanitizers (ASAN/TSAN) locally for complex C++ changes.
• No need to test or manual test.

Breaking Changes

• No

• Yes (Description: ...)

  Click to view Breaking Changes

  Breaking Changes:
  - Description of the breaking change.
  - Possible solutions or workarounds.
  - Any other relevant information.
  

[zhangxffff]

LGTM!