Add parse listener methods to Parser typescript

This PR adds the four parse listener methods. The `_parseListeners` field
could also be set to `ParseTreeListener[]`, but it would _technically_ be
a breaking change.

I chose to use `ParseTreeListener` instead of `any` in these methods because
parse listeners cannot actually be `any`; their functions are called without
checking if they're defined. The current ParseTreeListener interface is the
minimum requirement to avoid exceptions.

Signed-off-by: Phlosioneer <mattmdrr2@gmail.com>

runtime/JavaScript/src/antlr4/Parser.d.ts

@@ -6,6 +6,7 @@ import {ParserATNSimulator} from "./atn";
 import {Token} from "./Token";
 import {ParserRuleContext} from "./context";
 import {Printer} from "./utils";
+import {ParseTreeListener} from "./tree";
 
 export declare class Parser extends Recognizer<Token> {
 
@@ -24,6 +25,10 @@ export declare class Parser extends Recognizer<Token> {
  constructor(input: TokenStream);
  match(ttype: number): Token;
  matchWildcard(): Token;
+ getParseListeners(): ParseTreeListener[];
+ addParseListener(listener: ParseTreeListener): void;
+ removeParseListener(listener: ParseTreeListener): void;
+ removeParseListeners(): void;
  consume(): Token;
  enterRule(localctx: ParserRuleContext, state: number, ruleIndex: number): void;
  exitRule() : void;