Previously we support a limited case of function type deduction and in many places
we have to supply the type twice during set_body_typed (one in the template parameter, another in the lambda signature).

This PR improves the deduce function by enablng automatic function signature deduction.

```
TVM_REGISTER_GLOBAL("sub")
.set_body_typed([](int x, int y) -> int { return x - y; });
```

Unfortunately, because of template conflict, we can not support the original case
where both type signature and lambda are supplied through set_body_typed.

This PR refactors the existing regsitration to the new style.