Refactor WinGet app handling and add command overrides

Improves the reliability of WinGet app processing by making several key changes.

The build process now deletes the `WinGetWin32Apps.json` file before each run to ensure it is always freshly generated.

The UI no longer relies on `WinGetWin32Apps.json` to detect previously downloaded content. Instead, it checks directly for the application's content on disk, preventing unnecessary re-downloads.

This change also introduces a feature allowing users to override the default silent install commands for Win32 apps. By specifying `CommandLine` or `Arguments` properties in `AppList.json`, these values will be used to update the corresponding entries in `WinGetWin32Apps.json` during the build process.

FFUDevelopment/BuildFFUVM.ps1

@@ -5871,6 +5871,13 @@ if ($AllowVHDXCaching) {
         throw $_
     }
 }
+
+# Remove WinGetWin32Apps.json so it is always rebuilt next run
+if (Test-Path -Path $wingetWin32jsonFile -PathType Leaf) {
+    WriteLog "Removing $wingetWin32jsonFile"
+    Remove-Item -Path $wingetWin32jsonFile -Force -ErrorAction SilentlyContinue
+    WriteLog "Removal complete"
+}
 #Set $LongPathsEnabled registry value back to original value. $LongPathsEnabled could be $null if the registry value was not found
 if ($null -eq $LongPathsEnabled) {
     Remove-ItemProperty -Path 'HKLM:\SYSTEM\CurrentControlSet\Control\FileSystem' -Name 'LongPathsEnabled' -ErrorAction SilentlyContinue