WPF package to support .NET Core

[bruno-garcia]

Add a Sentry.Wpf package to support WPF apps on .NET Core 3.0+

• Making use of WinForms specific APIs that could enrich the event (name of the active Form?)
• One of the reasons for the <Reference System.* Won't go into Sentry package.
• If it's possible, with some #ifdef, making it work on Core and Fx.
• Update wizard and docs
• Clarify how it works in combination to a logging library integration

Similar to: https://github.com/getsentry/sentry-dotnet/issues/512

[bruno-garcia]

Consider using: https://github.com/snoopwpf/snoopwpf to get details of the view