Support for the file:// prefix

[Fokko]

Most IO implementations allow the file:// prefix to indicate that the data is local. Would be great if DuckDB can support this as well 👍

[kevinjqliu]

was searching through duckdb's codebase for file://, found that delta_scan can read file:// paths

https://github.com/duckdb/duckdb/blob/49a28e32aa68d6d9595612da185d75896571fc74/extension/delta/src/functions/delta_scan.cpp#L140-L163