Platforms that allow for configurable VOIP sample rates do not respect config values

Because of when GetEnumValueFromString (called by GetVoiceSampleRate) executes for certain modules at load time, the global enum master list is empty, which leads to the config value not being parsable.

As such, the session's sample rate becomes 16000Hz instead of the option specified in the configs. 

1. Add the following to DefaultEngine.ini

[/Script/Engine.AudioSettings]

VoiPSampleRate=Normal24000Hz

1. Start up the engine using Steam/NullOSS or any other platform that allows for configurable VOIP sample rates
2. Observe audio quality is not 24000Hz