Feature Request: wasm build for use with pglite

[SebastienGllmt]

Why do you want this feature?### What problem does the new feature solve?

pglite is a (relatively) new tool that allows running postgres in WASM (which allows it to run in-memory, or in the browser)

pglite supports some extensions built-in, but to add other extensions you need to compile them to WASM and register them with pglite yourself

What does the feature do?

This will allow using the duckdb extensions in WASM postgres instances, be it in-memory postgres running in a user process, or inside other environments that can run WASM such as the browser

Implementation challenges

• Although duckdb itself supports WASM compilation, we need to ensure that
  • this extension can compile to WASM (emscripten)
  • the wasm build of duckdb and the wasm build of this extension somehow combine properly in a way that can be used with pglite
• Need to distribute this build somehow. I created an issue for this in pgxman since this project uses it: Install package into .tar.gz for in-memory databases pgxman/pgxman#244

[JelteF]

I'm not opposed to this, but it's also definitely not anywhere near my top of the list of things to work on. Feel free to submit a PR though with changes that you need. I think we'd want a new make command like this: make -j20 DUCKDB_BUILD=ReleaseWasm