Failed to plan files: Invalid: Expected a local filesystem path, got a URI in PlanFiles() call in demo_example.cc

There is a "file:" prefix getting appended to the avro file path which leads to this error inside arrow localfs.cc (RETURN_NOT_OK(ValidatePath(path));) while running demo_example.cc on WIndows while making the PlanFiles() call.

iceberg-reader.exe "C:\iceberg_warehouse\db" sample "C:\iceberg_warehouse\db\sample\metadata\v5.metadata.json"
Failed to plan files: Invalid: Expected a local filesystem path, got a URI: 'file:/C:/iceberg_warehouse/db/sample/metadata/snap-4130091257426129961-1-0b7261a2-d123-4635-82a6-0a5a30e19a06.avro'

使用 demo_example.cc 和所示的 iceberg-reader.exe 命令重现 Windows 故障，然后跟踪 PlanFiles() 调用进入 arrow localfs.cc 和 ValidatePath(path)。当计划的 Avro 路径被接受为本地文件系统路径而不是 file: URI，并且演示成功完成时，工作即告完成。

由索引模型根据 Issue 内容生成。