Add themes interface for sounds

[Qchristensen]

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

Users have regularly asked for the ability to change NVDA's sounds. In some cases purely for personal customisation, and in some cases because other sounds are easier to hear or distinguish apart for some users Several issues which have existed for this include:

https://github.com/nvaccess/nvda/issues/931 (This issue may be separate, but requests alternate sounds for caps) https://github.com/nvaccess/nvda/issues/1007 https://github.com/nvaccess/nvda/issues/5382 https://github.com/nvaccess/nvda/issues/5978 https://github.com/nvaccess/nvda/issues/14068 (purely to change the startup sound which is often longer than the process which runs in the background)

Note that https://github.com/nvaccess/nvda/issues/9738 requests both ability to assign sounds to additional control types AND a sound theme manager. My recommendation is #9738 stay with the sounds for control types suggestion and THIS issue be the one for sound themes.

Describe the solution you'd like

Create a themes interface to allow users to change the existing NVDA sounds (please refrain from requesting adding sounds for new features on this issue, create a new issue for new functionality like that).

Describe alternatives you've considered

Discussing with @seanbudd the suggestion was made for a themes interface for plugins. A type of add-on that's just sound profiles, gestures/symbols dictionary files, braille tables, settings configs, etc. THIS issue will only concentrate on sounds, but the intention is to build the interface backend which can be used for those other purposes in time.

Additional context

Back in 2017, Jamie Teh created new sounds for NVDA - https://github.com/nvaccess/nvda/pull/7218 - the specific sounds divided opinion but the idea of being able to change the sounds was very popular. In reverting it (we didn't want to make a change which wouldn't either be overwhelmingly popular or at least customisable so you could keep the existing behaviour), the intention was to add an interface to let user change the sounds (without needing to go in and manually move wav files around in Explorer).