(chocolateyGH-739) Fix: Update templates to use extension

Templates are set to use the chocolatey-uninstall.extension helper by default.
The helper includes a catch for invalid registry keys. Using the catch is a
requirement as blindly enumerating will fail every time if even one invalid key
exists.

src/chocolatey/infrastructure.app/templates/ChocolateyUninstallTemplate.cs

@@ -54,13 +54,8 @@ public class ChocolateyUninstallTemplate
 }
 
 $uninstalled = $false
-$local_key     = 'HKCU:\Software\Microsoft\Windows\CurrentVersion\Uninstall\*'
-$machine_key   = 'HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\*'
-$machine_key6432 = 'HKLM:\SOFTWARE\Wow6432Node\Microsoft\Windows\CurrentVersion\Uninstall\*'
-
-[array]$key = Get-ItemProperty -Path @($machine_key6432,$machine_key, $local_key) `
-                        -ErrorAction SilentlyContinue `
-         | ? { $_.DisplayName -like ""$softwareName"" }
+# Get-UninstallRegistryKey is provided by the chocolatey extension package "chocolatey-uninstall.extension" and must be included as a dependency in this package's nuspec if used.
+[array]$key = Get-UninstallRegistryKey -SoftwareName $softwareName
 
 if ($key.Count -eq 1) {
   $key | % { 

src/chocolatey/infrastructure.app/templates/NuspecTemplate.cs

@@ -80,6 +80,8 @@ public class NuspecTemplate
       <dependency id="""" version=""[_MIN_VERSION_INCLUSIVE, MAX_VERSION_INCLUSIVE]"" />
       <dependency id="""" version=""[_MIN_VERSION_INCLUSIVE, MAX_VERSION_EXCLUSIVE)"" />
       <dependency id="""" />
+      <!-- If including a chocolateyUninstall.ps1 file to uninstall an EXE/MSI or similar installable program, you most likely will require the chocolatey-uninstall.extension package. Please verify whether you are using a helper function from that package. -->
+      <dependency id=""chocolatey-uninstall.extension"" />
     </dependencies>-->
 
     <!--<provides>NOT YET IMPLEMENTED</provides>-->