Avalonia: 0.9.12 => 0.10.6 . Address breaking changes

[strazto]

In particular:

• Avalonia.Serilog Namespace:
  • Remove references to Avalonia.Serilog
  • Change reference from LogToDebug() => LogToTrace()
• MessageBoxView:
  • WindowBase.Owner { set } is now protected, so add Window owner to constructor.
• Avalonia.Diagnostics:
  • Install Avalonia.Diagnostics separately, as it appears to have migrated into own package.