(chocolatey#911) Add missing disabling of install buttons

This commit updates both the install and the advanced install
buttons to be disabled if the user running the application are
not allowed to install any backages (only relevant when a
Chocolatey licensed and Chocolatey GUI licensed extensions
are installed).

Source/ChocolateyGui.Common.Windows/Views/PackageView.xaml

@@ -1,4 +1,4 @@
-<UserControl x:Class="ChocolateyGui.Common.Windows.Views.PackageView"
+<UserControl x:Class="ChocolateyGui.Common.Windows.Views.PackageView"
              xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
              xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
              xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
@@ -70,6 +70,7 @@
                             </StackPanel>
                         </Button>
                     <StackPanel Orientation="Horizontal"
+                                IsEnabled="{Binding IsInstallAllowed}"
                                 Visibility="{Binding IsInstalled, Converter={StaticResource BooleanToVisibility}, ConverterParameter=True}">
                         <Button Padding="10" Margin="5 0"
                             Command="{commands:DataContextCommandAdapter InstallAdvanced}">
@@ -85,6 +86,7 @@
                         </Button>
                     </StackPanel>
                     <StackPanel Orientation="Horizontal"
+                                IsEnabled="{Binding IsInstallAllowed}"
                                 Visibility="{Binding IsInstalled, Converter={StaticResource BooleanToVisibility}, ConverterParameter=True}">
                         <Button Padding="10" Margin="5 0"
                             Command="{commands:DataContextCommandAdapter Install}">