Implicitly convert function to delegate

[dlangBugzillaToGithub]

Marcelo Silva Nascimento Mancini reported this on 2023-01-11T14:39:11Z

Transferred from https://issues.dlang.org/show_bug.cgi?id=23621

Description

```d
import std.stdio;
int add(int delegate() a, int delegate() b){return a()+b();}
int getNumber(){return 50;}
void main()
{
    writeln(add(&getNumber, &getNumber));
}
```

This currently does not compile,  so it is needed tu wrap