Support enableWordTimeOffsets and output_format_config for speech-to-text captions output

[wongcain]

[READ] Step 1: Are you in the right place?

Issues filed here should be about a feature request for a specific extension in this repository. To file a feature request that affects multiple extensions or the Firebase Extensions platform, please reach out to
Firebase support directly.

[REQUIRED] Step 2: Extension name

This feature request is for extension: speech-to-text

What feature would you like to see?

Please include configuration options for enableWordTimeOffsets and output_format_config in order to produce output that is usable in an app for captions as described here: https://cloud.google.com/speech-to-text/v2/docs/caption-support

How would you use it?

To display captions over playing audio.

[cabljac]

Closing this as unplanned. We can reopen if more interest is demonstrated.