Support component model `map<K, V>`

[celarye]

A while back the component model introduced map<K, V> (WebAssembly/component-model#554). I have a WIT interface which imports this, which I think might be the cause for the following ComponentizeJS panic:

thread '<unnamed>' (1) panicked at crates/spidermonkey-embedding-splicer/src/bindgen.rs:857:18:
internal error: entered unreachable code
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
An error occured while building the WASI component: RuntimeError: unreachable

ComponentizeJS/crates/spidermonkey-embedding-splicer/src/bindgen.rs

Line 857 in 12c2b4a

_ => unreachable!(),