autoload('parquet') since it's needed for scan_parquet

[carlopi]

In case of duckdb-wasm (potentially also in other configurations) parquet might not be already loaded.

This makes so that in those cases error change from:

LOAD delta;

Invalid Input Error: Initialization function "delta_init" from file "/Users/carlo/.duckdb/extensions/v1.1.3/osx_arm64/delta.duckdb_extension" threw an exception: "Function with name "parquet_scan" not found in ExtensionUtil::GetTableFunction"

to either successfully autoinstalling or autoloading parquet OR informing that there has been an autoloading problem with the parquet extension.

This is minor, and should not change any currently tested code-path.

[samansmink]

Looks good, thanks!