[python] Use urlpath.URL to replace pathlib.Path to avoid scheme missing in pypaimon

[XiaoHongbo-Hope]

Purpose

Fixes URI scheme loss issue in blob-as-descriptor mode by replacing pathlib.Path with urlpath.URL throughout the codebase. This ensures URI schemes (e.g., oss://, s3://, file://) are preserved when handling blob descriptors and file paths.

Key Changes

1. Replaced pathlib.Path with urlpath.URL: Unified path handling to preserve URI schemes across all filesystem operations.

2. Dependency: Added urlpath==2.0.0 as a required dependency.

Impact

• FileIO: All methods now accept URL type instead of Path
• FileSystemCatalog: Returns URL objects for database and table paths
• DataFileMeta.set_file_path: Accepts URL type
• SchemaManager: Uses URL for table paths
• UriReader.get_file_path: Returns URL instead of Path

Tests

• test_blob_write_read_end_to_end_with_descriptor: Verifies URI scheme preservation in blob descriptors
• Sample script oss_blob_as_descriptor.py: Demonstrates OSS blob-as-descriptor functionality with scheme preservation