[AudioTranscoding] Add FLAC as supported target audio format and be able to define the corresponding target sample rate

CONTRIBUTORS.md

@@ -104,6 +104,7 @@
  - [sorinyo2004](https://github.com/sorinyo2004)
  - [sparky8251](https://github.com/sparky8251)
  - [spookbits](https://github.com/spookbits)
+ - [ssenart] (https://github.com/ssenart)
  - [stanionascu](https://github.com/stanionascu)
  - [stevehayles](https://github.com/stevehayles)
  - [SuperSandro2000](https://github.com/SuperSandro2000)