This PR add support for %type declarations using `%nterm` in Nonterminal Symbols.
https://www.gnu.org/software/bison/manual/html_node/Type-Decl.html

In bison when a terminal symbol is passed to `%nterm` it should give an error. But it doesn't yet.
It just ignores the terminal symbol and uses the nonterminal symbol.

For example in the following code, `EOI` is a terminal symbol and `EOI` is a nonterminal symbol. When `EOI` is passed to `%nterm` it should give an error but it doesn't.

```yacc
%{
// Prologue
%}

%token EOI 0 "EOI"
%nterm EOI

%%

program: /* empty */
        ;
```

In bison, it gives the following error

```
❯ bison test.y
test.y:6.8-10: error: symbol EOI redeclared as a nonterminal
    6 | %nterm EOI
      |        ^~~
test.y:5.8-10: note: previous definition
    5 | %token EOI 0 "EOI"
      |        ^~~
```

So this PR adds an error when a terminal symbol is passed to `%nterm`.