Try next synth if oneCore consistently fails (#12647)
Fixes #10451 and fixes #11544
Summary of the issue:
#10451
OneCore voices silently fail when attempting to speak an alphabet they don't support (eg an English voice reading Cyrillic characters). This makes installing NVDA for the first time for the first time inaccessible if someone is using a system with a language that isn't supported by their OneCore installed voices.
#11544
An issue was raised on #11543 where oneCore failed to initialise, causing all speech to fail.
If no speech succeeds, the _player is never set and so a subsequent error is thrown in _processQueue.
Description of how this pull request fixes the issue:
#10451
When picking a synthesizer automatically (using "auto", ie not overriden by a user), fail if the current NVDA language and current system language is not supported by installed OneCore voices.
#11544
If oneCore fails to speak more than N=5 times in a row, try the next synth on the synth priority list.
