[Wasm][KeyPath] Resolve absolute function pointer as identity
Emit and resolve idValue of KeyPath as an absolute pointer if relative
function pointer is turned-off on Wasm target.
The existing ABI can't distinguish an idValue between function pointer
or data pointer in use-site at compile-time and also at runtime. So this
patch adds a new id resolution scheme `ResolvedAbsolute` to distinguish
them at runtime properly.
