speechmatics: expose properties for controlling punctuation joining

By default the transcriber will attempt to join punctuation with the preceding word, expose a property to control that.

As speechmatics sometimes outputs punctuation for a sentence in the next transcript, it will sometimes arrive too late for joining. In order to work around this behavior, a lower max-delay is used by default, that may not always be desirable, especially if low latency is a concern.

Expose a property to disable the hack.