Changes to handle #15150
Follow up to #14697, #14896, #15038, #15097, #15145

Summary of the issue:
WASAPI usage is known to cause intermittent crashing in #15150.
Generally, WASAPI code has not been proven to be stable.
Due to this, it should not be enabled by default in 2023.2.
WASAPI can be re-enabled by default once it is proven to be stable.

Description of user facing changes
Disable WASAPI by default, preventing intermittent crashing #15150

Description of development approach
Turn the WASAPI checkbox into a feature flag, so that it can easily be re-enabled in future.

Testing strategy:
Manual testing
Upgrading the profile: Test starting NVDA with the WASAPI config value set to "True/False" instead of a "enabled/disabled/default".

Test the various controls related to WASAPI - ensure they are saved, applied and respected correctly.