Assembly builtins share the namespace with solc symbols

```
function keccak256(input: memory(bytes)) -> bytes32 {
let ptr : word = Typedef.rep(input);
let res : word;
assembly {
res := keccak256(add(ptr, 32), mload(ptr))
}
return bytes32(res);
}
```

Results in:
```
Type error:
Arity mismatch in call to keccak256
expected 1 argument(s)
found 2

Error: yule generation failed
```

So assembly builtins/functions are in the same namespace as solc symbols? Yet they are not accessible there (and only local solc non-functions are available in yul), so I would assume this should not be the case (and is not in solidity). I'd argue that may not be optimal.