Add intermediate quality options: 32-40 kbit/s with ≥20 kHz sample rate for Opus

[Self-Perfection]

Checklist

• I made sure that there are no existing issues - open or closed - to which I could contribute my information.
• I made sure that there are no existing discussions - open or closed - to which I could contribute my information.
• I have read the FAQs inside the app (Menu -> About -> FAQs) and my problem isn't listed.
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• This issue contains only one feature request.
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Feature description

I would like to be able to set sample rate to >=20 kHz for any bitrate in range 32-40 kbit/sec.

Why do you want this feature?

I would like to make voice recordings transparent, without noticeable quality degradation.

At the moment I am forced to select 64 kbit/sec.

I am quite sure that opus codec can encode voice transparently at 32 kbit/sec given possibility to do so: if #196 is fixed and sampling rate set to >=20 kHz. Even without fixing #196 at 40 kbit/sec CBR opus should be quite good.
See https://wiki.hydrogenaudio.org/index.php?title=Opus for instance for confirmation.

Enabling higher sampling rate for 32 kbit/sec will allow me to reduce size of my audio recordings 2x times.

Additional information

No response

Proposed implementation

Add quality presets:

• 32 kbit/s @ 24 kHz (Voice High Quality)
• 40 kbit/s @ 24 kHz (Voice Premium)
• Keep existing 64 kbit/s @ 48 kHz option