Support All US IPA Chars

[rmtuckerphx]

The full list of IPA characters supported by Alexa is shown here:
https://developer.amazon.com/docs/custom-skills/speech-synthesis-markup-language-ssml-reference.html#phoneme

This includes the following chars: d͡ʒ and t͡ʃ

The file SpeechMarkdownGrammar.ts has been updated to include those chars, but when testing in ipa-standard-alphabet-us.spec.ts the tests error.

Solution: add the chars to the tests and get them to pass.

[rmtuckerphx]

@Fleker Can you figure out why adding these chars to the test cause it to fail?

[Fleker]

I'll take a look. It may be due to some unicode mismatch.