[Build] trgen not generating correct tester.pm1 for Java

[kaby76]

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This is a minor problem for now, but could be a blocking problem later on. trgen does not generate a correct line for compiling all sources in tester.pm1. All java sources found should be added.

$msg = javac -cp "C:/Users/Kenne/Downloads/antlr4-4.10.1-complete.jar;." JavaScriptLexer.java JavaScriptParser.java  Program.java ErrorListener.java

This PR adds code for formatting JavaScript, but it's not in the javac compilation here. (Why it's being added to the parser is another issue.)