This commit changes the C API function `wasm_module_new` to use the Rust API
`Module::from_binary` which performs verification of the module, as per the C
API spec.
This also introduces a `EngineBuilder` type to the C# API that can be used to
construct an `Engine` with the various Wasmtime configuration options. This
is required to get the C# tests passing since they use reference types and
multi-value.
Fixes#859.
7dfb6ebdb6