closes #45

In addition to changes below, this PR also improves the build process, as well as enabling code formatting for TS/Java on commit. Files have been formatted, so changes are quite noisy.

From Changelog:

• (BREAKING) Migrated from antlr4ts to official antlr4 runtime package.
  • Some lesser used methods are missing in the type definitions, refer to the antlr4 Javascript code if you need to cast types.
  • extends is now required to use antlr Listener/Visitor types.

    • Exception being to avoid the property initialisation syntax in the antlr generated types:

      class MyListener extends ParseTreeListener implements ApexParserListener {
        // with 'extends ApexParserListener' you must write this
        enterMethodDeclaration = () => {}
        // this requires 'extends ParseTreeListener implements ApexParserListener'
        enterMethodDeclaration() {}
      }

• (BREAKING) Updated output to ES2020 and increased min node version to 16.
• (BREAKING) Updated to ANTLR 4.13.2 across both distributions. Same tool now generates both.
• (BREAKING) Re-exported antlr types removed, add antlr4 package dep instead matching apex-parser version.
• Typescript CaseInsensitiveInputStream type now extends CharStream and can be constructed from string.
  • Constructor passing in Charstream retained to match Java version.
• Removed node-dir dependency - replaced with node fs api.