[Codec] Opus for Windows

[Spoon]

Using the latest Opus v1.1.1 libraries.

[Spoon]

Updated to R5 using Opus v1.1.4

[Spoon]

Updated to R7, using Opus 1.3:

Improvements to the VAD and speech/music classification using an RNN
Support for ambisonics coding using channel mapping families 2 and 3
Improvements to stereo speech coding at low bitrate
Using wideband encoding down to 9 kb/s
Making it possible to use SILK down to bitrates around 5 kb/s
Minor quality improvement on tones
Enabling the spec fixes in RFC 8251 by default
Security/hardening improvements

[Spoon]

Updated to R7.1 using Opus 1.3.1