What does this PR fix?

• Go runtime missing export of "Reset()" #3441 (Go target)
• Go runtime missing export of "String()" #3443 (Go target)

Discussion

This is a fix for the missing API method String() in the Token, and Reset() in the Lexer.

Go requires any exported data or functions to be capitalized. These functions are required for this code to print out the token stream:

    j := 0
    for {
        t := lexer.NextToken()
        fmt.Print(j)
        fmt.Print(" ")
        // missing fmt.Println(t.String())
        fmt.Println(t.GetText())
        if t.GetTokenType() == antlr.TokenEOF {
            break
        }
        j = j + 1
    }
    // missing lexer.Reset()

IToken.ToString() in C# and Token.toString() in Java are available because whatever implementation is used, it is derived from object. Thus, in C#, you can do t.ToString() or Java, t.toString(). Yet, t.String() in Go causes a compilation error.

Reset() in C# and reset() in Java are explicitly listed public in the interface. Thus, in C#, you can do lexer.Reset();, and Java, lexer.reset();. Yet, lexer.Reset() or lexer.reset() in Go results in a compilation error.

The change is renames two methods. I've included a test in the runtime for the two methods.

Why is this PR important?

grammars-v4 CI tests most of the Antlr targets on a per-commit basis. The CI testing has pointed to many important bugs in Antlr. When a difference in parsing is detected, we need ways to easily compare the computations of the target with other targets. A print out of the tokens during the parse is absolutely essential in discovering why a parser target is not working.