This PR makes `PlatformWasm` a `RemoteAwarePlatform` that can connect to
a remote GDB platform server. `PlatformWasmRemoteGDBServer` inherits
from `PlatformRemoteGDBServer`, with the only difference that it picks
the correct Process plugin when launching and attaching. The approach is
identical to the one taken by `PlatformAndroid`.
The context is that we're working on a platform based approach for
discovering and attaching Wasm processes running under JSC with the
[newly added debugging
support](https://github.com/WebKit/WebKit/pull/51462).
