Make BasePermission.permission public

[cannorin]

Related: #148

When working with the new API in shared .NET standard projects, we often have to use ShouldShowRequestPermissionRationaleAsync which does not accept type parameters.

Since member BasePermission.permission : Permission is not public, we have to write a mapping from type to enum like below:

type Permission<'Permission when 'Permission :> BasePermission and 'Permission: (new: unit -> 'Permission)>() =
    static member val Value: Permission = Permission.Unknown with get, set
do
    Permission<CalendarPermission>.Value <- Permission.Calendar
    Permission<CameraPermission>.Value <- Permission.Camera
    Permission<ContactsPermission>.Value <- Permission.Contacts
    Permission<LocationPermission>.Value <- Permission.Location
    Permission<LocationAlwaysPermission>.Value <- Permission.LocationAlways
    Permission<LocationWhenInUsePermission>.Value <- Permission.LocationWhenInUse
    Permission<MediaLibraryPermission>.Value <- Permission.MediaLibrary
    Permission<MicrophonePermission>.Value <- Permission.Microphone
    Permission<PhonePermission>.Value <- Permission.Phone
    Permission<PhotosPermission>.Value <- Permission.Photos
    Permission<RemindersPermission>.Value <- Permission.Reminders
    Permission<SensorsPermission>.Value <- Permission.Sensors
    Permission<SmsPermission>.Value <- Permission.Sms
    Permission<SpeechPermission>.Value <- Permission.Speech
    Permission<StoragePermission>.Value <- Permission.Storage

If you could make it public, it will make ShouldShowRequestPermissionRationaleAsync a lot easier to use.

[jamesmontemagno]

My plan will be to remove all old methods and to move over the rationale to also use the new system.

[paul-kiar]

Please make this API consistent with the new system. I have the same issue.