Bug fixing + new extensions to parse Media Services Encoder metadata and generate HLS v3 URL

- Added new extension methods for IAsset and IAssetFile to parse the Media Services Encoder Metadata out of the metadata asset file
- Added new IAssetFileExtensions class and moved there all the IAssetFile extensions
- Added extensions methods for IAsset and ILocator interfaces to get the HLS version 3 Streaming URL
- Added new unit tests
- Updated README.md with documentation for the new extensions
- Added ConfigureAwait(false) to all 'async/await' operations to avoid potential deadlocks