Ability to record audio into a stream

### Description

This is a straight up copy from the Xamarin.Essentials Ticket where the Pull Request war done several years ago but never got reviewed after the initial stage. The implementation is completed for UWP, iOS and Android. https://github.com/xamarin/Essentials/pull/723

### Public API Changes

```csharp
public static class Recorder
{
public static Task CanRecordAudio => PlatformCanRecordAudio;

public static bool IsRecording { get; private set; }

public static async Task RecordAsync();

public static async Task StopAsync()
}

public class RecordedAudio : IDisposable
{
public Stream AsStream();
public string Filepath {get;}
}

### Intended Use-Case

Recording audio on smartphones and other devices is integral to various use cases.