mod_google_transcribe: Feature Request: Allow google speech to text endpoint to be configurable

[entenschnabel]

Currently the uri used to specify the endpoint for google's speech to text service is hard coded to the default "speech.googleapis.com" in the GStreamer class in google_glue.cpp. It would be useful to make this uri configurable so that we can be GDPR compliant and use e.g. ""eu-speech.googleapis.com" instead.