fix(core): only install vscode extension if its not already installed

When installing a vscode extention the shell command to install the extention
would run every time puppet was run. Now we test to see if the extention is
installed first before trying to install it.

site-modules/vscode/manifests/extention.pp

@@ -2,6 +2,7 @@ define vscode::extention {
   exec { "code_install_${title}":
     command  => "code --install-extension ${title}",
     path     => '/usr/bin:/usr/local/bin:/usr/sbin:/bin',
+    unless   => "code --list-extensions | grep ${title}",
     provider => shell,
   }
 }