fix(datafusion): avoid loading tables for SHOW TABLES

[shyjsarah]

Purpose

Linked issue: close #575

SHOW TABLES should use catalog metadata without opening every listed table. The default DataFusion SchemaProvider::table_type implementation calls table(name), which can initialize FileIO and turn a metadata-only operation into a table access.

Brief change log

• collect base-table and view types while listing catalog objects
• override PaimonSchemaProvider::table_type to use the collected metadata instead of loading table providers
• preserve temporary table/view precedence and catalog view classification
• keep direct table reads on the existing lazy-loading path
• add regression coverage for unavailable table loading and catalog view types

Tests

• cargo fmt --all -- --check
• cargo test -p paimon-datafusion --test sql_context_tests
• cargo clippy -p paimon-datafusion --all-targets -- -D warnings

API and Format

No public API or storage format changes.

Documentation

No documentation changes are required.

[JingsongLi]

+1