Allow passing imports to instantiateWasm

[keller-mark]

This would enable passing JS functions that can be exposed to custom DuckDB-WASM extensions. I want my extension code to be able to call a JS function that I specify and provide via the imports parameter of instantiateWasm.

While there is already createScalarFunction, this is only for scalars. This does not allow my JS function to have an arbitrary return value, such as a whole arrow column vector or table.

duckdb-wasm/packages/duckdb-wasm/src/bindings/bindings_browser_base.ts

Line 39 in ff93f70

imports: any,