Rename of functions with same name but different signatures
### Summary

The @name smarttag doesn't seems to work when renaming functions with the same name but different signatures

Version 4.12.11

### Steps to reproduce

The following code demonstrates the problem:
~~~
drop function if exists func(integer);
drop function if exists func(integer, integer);

create function func(i integer) returns integer as $$
  select i
$$ language sql;

create function func(i integer, j integer) returns integer as $$
  select i + j
$$ language sql;

comment on function func(integer) is E'@name func1';
comment on function func(integer, integer) is E'@name func2';
~~~
### Expected results

When creating a new mutation, I would expect the renamed functions 'func1' and 'func2' to show up in GraphiQL

### Actual results

Neither the renamed functions nor the original functions are available in GraphiQL

