support pass buffer directly between two modules

[scottlin2019]

like this:

char *invokeModule(wasm_exec_env_t exec_env, uint32 *argv[], int argc)

[xwang98]

@joshtriplett Is any spec proposal that might be related to this issue?

[xwang98]

@abrown pointed this propsoal: https://github.com/WebAssembly/interface-types/blob/master/proposals/interface-types/Explainer.md#enabling-shared-nothing-linking-of-webassembly-modules

@scottlin2019

[joshtriplett]

Passing a buffer between modules would definitely require some sort of memory-to-memory copying, at least at the moment, since modules wouldn't share a linear memory. That's part of what interface types should help to specify.