[orca-list] The "Break speech into chunks between pauses" should have more functionality now

[Joanmarie Diggs <jdiggs igalia com>]

Hey all.

While looking into another issue, I discovered that "Break speech into
chunks between pauses" was doing next to nothing. Now it controls when
pauses are explicitly added by Orca to break up speech. Please test and
let me know if you find any regressions resulting from this change.

On a related note, I'm sure someone is about to mention pauses in SayAll
in web content. That is still on my to-do list and not the result of
Orca deliberately/explicitly adding pauses.

--joanie