Forwards compatibility with WASI/WASM

[bmeck]

It seems we have some research to do about how WASI expects to run as entry points vs modules. This is just a tracking issue for now to figure out forwards compatibility for node ./foo.wasm or node ./foo.wasi w/e we need to do.

CC: @cjihrig

[bmeck]

• esm: empty ext from pkg type/main doesnt affect format node#31021 appears to need to be done to ensure we don't load node bin/foo.wasm as ESM like we currently do.

[bmeck]

cross ref: WebAssembly/esm-integration#32