Missing C API for inspecting Memory?

[TerrorJack]

Currently, there is BinaryenSetMemory in C API, but we don't have something like BinaryenGetMemory which ideally would allow us to inspect the data segments of a module, given a deserialized BinaryenModuleRef.

Having such an interface allows a wasm-targeting compiler based on binaryen to perform a simple sanity check: deserialize the generated module, and check if the deserialized data segments match the ones we feed to binaryen but represented in another language.