[SpeechRecognition] Add ability to transcribe audio files to text

[DelphiWorlds]

This is something I have had in research for a while - presently I have code for macOS, but it should be possible on iOS also. Needs further research for Android and/or Windows

[DelphiWorlds]

For anyone following: I am going to add the iOS/macOS implementation soon. It appears for Android it will require using Google Cloud APIs. If there's enough interest, I may look into this.