The `wasm_trap_t**` argument of `wasm_instance_new` represents an
output pointer to a `wasm_trap_t*`, not an array of
`wasm_trap_t*`. This patch updates the code accordingly.
When running `Instance::new`, it can error with an
`InstantiationError`. There is 2 scenarii:
1. Either it's a `InstantiationError::Link`. In this case, the
`wasm_instance_new` function must return `NULL` and register the
error in the Wasmer error registry.
2. Either it's a `InstantiationError::Start`. In this case, the
`wasm_instance_new` function must return `NULL` and the error must be
converted into a `wasm_trap_t`, which is stored in the `wasm_trap_t**`
array. This array is initialized by `wasm_instance_new` itself.
`wasm_store_t` is now a proper struct (rather than an opaque type) of
kind:
```rs
struct wasm_store_t {
inner: Store
}
```
The rest of the patch updates the code accordingly.
