Working with GC types without copy

I'm having some trouble switching to wasi preview 2.

For example, the following interface:

package wasi:random@0.2.0;
interface random {
    get-random-bytes: func(len: u64) -> list<u8>;
}

The function signature is func (u64) -> (list<u8>)

But its lower type is core func (i64, i32) -> (), which is very difficult to use.

If I want to convert it to core type (array (mut u8)), a very long glue code is required.

I hope to add a GC mode canon option that can make the lower type similar to core func (i64) -> (array u8).

For complex nested types, getting the specified data requires very complex pointer algebra, whereas if using array it only requires multiple array.get.

I think this helps simplify the use of some external interfaces, such as:

package wasi:filesystem@0.2.0;
interface preopens {
    get-directories: func() -> list<tuple<descriptor, string>>;
}

Start by reviewing the issue's WASI Preview 2 WIT examples and the stated lower signatures for random and preopens. Investigate how the proposed GC mode canon option would affect list and nested list<tuple<descriptor, string>> lowering. Done should be a clearly specified, reviewed design for the option and its compatibility with these examples.