Allow OnDetachedFromLogicalTree to be fired > once.
Allow OnDetachedFromLogicalTree to be fired > once.

As it can happen now that TemplatedControl is correctly detaching
template children.

punker76/Perspex,jkoritzinsky/Perspex,grokys/Perspex,wieslawsoltes/Perspex,MrDaedra/Avalonia,MrDaedra/Avalonia,SuperJMN/Avalonia,jkoritzinsky/Avalonia,OronDF343/Avalonia,grokys/Perspex,wieslawsoltes/Perspex,wieslawsoltes/Perspex,SuperJMN/Avalonia,jkoritzinsky/Avalonia,AvaloniaUI/Avalonia,AvaloniaUI/Avalonia,jkoritzinsky/Avalonia,SuperJMN/Avalonia,jkoritzinsky/Avalonia,SuperJMN/Avalonia,wieslawsoltes/Perspex,AvaloniaUI/Avalonia,susloparovdenis/Avalonia,SuperJMN/Avalonia,Perspex/Perspex,wieslawsoltes/Perspex,AvaloniaUI/Avalonia,jazzay/Perspex,SuperJMN/Avalonia,susloparovdenis/Perspex,wieslawsoltes/Perspex,SuperJMN/Avalonia,OronDF343/Avalonia,akrisiun/Perspex,AvaloniaUI/Avalonia,AvaloniaUI/Avalonia,susloparovdenis/Avalonia,wieslawsoltes/Perspex,Perspex/Perspex,AvaloniaUI/Avalonia,jkoritzinsky/Avalonia,jkoritzinsky/Avalonia,susloparovdenis/Perspex,jkoritzinsky/Avalonia