[orca-list] Initial commit of sound support done -- NOT hooked up quite yet

[Joanmarie Diggs <jdiggs igalia com>]

Hey all.

As the subject states, we're are very close to having progress bar
beeps. We're also very close to having full, customizable sound icon
support. But I deliberately didn't hook either up. So you'll see the
commit and hear no change. That's on purpose. As I stated in the commit
message:

Note: I attempted to create the progress bar beep Tone based on Chrys'
patch, but it doesn't sound right. Once he fixes that, progress bar
beeps will be hooked up.

Once I finish testing the sound icon support, it will be hooked up as
an "experimental" feature to be refined and GUI-ified during the 3.21/22
cycle.

Stay tuned!
--joanie