Multi-file implicit map/array wasm wrappers - where to declare? #138

We need to standardize where to declare map/array wasm wrappers when they're implicit e.g.:

foo = {
    implicit_arr: [* bar]
    implicit_map: { * abc => xyz }
}

Currently it's fine when there's only one file they could exist in but this could potentially not be the case.

Some first possibilities are:

1. declare where the element is declared
2. declare where it was used

However for maps 2) is problematic as there are potentially two types and for both both 1)/2) are problematic as there could be two different areas using the same type implicitly potentially.

We could potentially either:

1. Make a priority where it goes something like: try where element(s) declared -> try where used -> lib.rs as fall-back if neither are consistent
2. Just always put them in lib.rs (can be weird e.g. why is TransactionBodyList in lib.rs when it's only used in block.rs and TransactionBody is in transaction.rs?)