Add a speakup module

[sthibaul]

Is your feature request related to a problem? Please describe.

Hardware synths cannot be used in Orca

Describe the solution you'd like

Adding a module to speech-dispatcher that emits text to /dev/synth would let orca access speakup-driven hardware synthesizers.

Additional context

requested on
https://www.freelists.org/post/orca/Can-Orca-work-with-hardware-synthesizers