Fix audio issues on Windows, properly handle default config values

[neilenns]

I'm lucky, on Windows my audioApi value is 0. This exposed a host of problems in the code that tested the value of audioApi using logical or. This resulted in a default value of -1 being used when calling afv-native, and basically broke all audio.

Changes:

• Create a new defaultConfiguration object that defines the default value for all configuration properties
• When reading a saved configuration from storage first apply the default configuration, then apply the saved values. This ensure the currentConfiguration object always has a value for all the properties, even if it's first run of the app or one of the properties was manually deleted from the saved config.
• Remove places in the code that used || as a method of catching undefined/invalid configuration values since that can't happen anymore

Verified on Windows the following works:

1. Deleting the audioApi property from a config file
2. Selecting an audio API in settings after running with the value missing from the saved config. Result is the UI magically updates and properly shows the saved output and input devices. Yay.
3. Rx works, tested via listening to KPDX_ATIS in an OBS session

[neilenns]

I think if eslint had @typescript-eslint/stylistic-type-checked rules enabled it would have caught this before it was a problem. The https://typescript-eslint.io/rules/prefer-nullish-coalescing/ rule specifically prefers ?? over || for this very reason.

I might try enabling that and see what else it finds...