Add support for Streaming STT (realtime)

[Swimburger]

Currently, we don't have plans to add support for Streaming STT.
We will reconsider this decision if there is enough demand for Streaming STT in Ruby.
Add a 👍 to this issue if you want Streaming STT support or leave a comment.

[son1112]

How open are you to public contribution toward this effort?

[Swimburger]

@son1112, we'd be happy to accept it as a contribution.
The only condition is that it should be clear that we don't officially support it, either via its name or some other way to mark it as experimental.