WIP: Clippit 2.0

[sergey-tihon]

• [x] Migrate to .NET 6
• [x] Remove dependency on System.Drawing
• [x] Add Tiff support ImageSharp v2.0
• [ ] Wait for release SixLabors.Fonts & SixLabors.ImageSharp.Drawing

[sergey-tihon]

This is really bad ...

System.TypeInitializationException : The type initializer for 'Gdip' threw an exception. ---- System.PlatformNotSupportedException : System.Drawing.Common is not supported on non-Windows platforms. See https://aka.ms/systemdrawingnonwindows for more information.