Suggestion: Mobile voice experience, implement microphone input subsystem settings to troubleshoot or improve sound

The problem:

When making a Discord call from the mobile app, the CALL microphone mixer path is chosen, which tells the phone to use its own "call processing" onto the microphone signal before it's sent to Discord that can not be controlled by the end user, although the user can control the discord post-processing. 

Additionally, this call mode may also trigger their phone or headset's audio output quality to become degraded

The problem explanation:

This call optimization can have various levels of audio impact based on the phone model, it can range from nothing (in rare cases), to tolerable, to being bad enough that talking from a distance produces very unintelligible audio. 

Other VOIP apps such as snapchat don't seem to be defaulting to "Call" microphone mode as they don't induce this issue

The idea:

Give the end-user some kind of ability to choose what microphone input subsystem they want discord mobile to use in calls.

This can benefit users who wish to either debug audio issues, or for power-users to improve their sound.

Examples of possible implementation strategies:

1. Be a setting people can opt into, with the default microphone mode maybe remaining the same
2. It could be considered an "advanced" option, maybe locked behind developer mode, and/or placed at the bottom of "Voice" settings
3. The setting could be a small button within the "audio output" menu
4. "Call" and "VOIP Communication" at bare minimum, although extra options such as "Unprocessed" would be extra appreciated