Let auto splitters hand in the Unity runtime module (#174) - #196

Part of #174.

The scene manager, Mono and IL2CPP can now attach to a module the auto splitter finds itself. Each has attach_to_module(process, module, profile) and wait_attach_to_module, which take the module's address like Unreal's attach and Godot's locate do. This covers a renamed runtime file and a game with the engine in its executable, and none of it needs alloc.

let module = process.get_module_address("Game.exe").ok()?;
let manager =
    SceneManager::attach_to_module(&process, module, profiles::UNITY_5_6_2F1_WINDOWS_X86_64)?;

• The format and size come from the module's header. A PE image takes its size of image and an ELF image runs to the end of its last load segment, the range GameAssembly.so already gets for its globals in .bss.
• Mono trusts the profile's library instead of guessing it from the file name.
• Mach-O isn't supported here, since asr has no reader for a Mach-O image's size yet.

cargo test --all-features and cargo test --no-default-features --features unity. The new tests attach each module under a file name attach doesn't know and read PE and ELF sizes from headers. I also ran all 93 Linux and Windows fixture players on it.

Depends on #195.