PowerToys Run cache issue (#4472)

* Clean termination of powertoys process.

* Fixed issue with run not responding to WM_CLOSE

* Fixed serialization error in pinyin and image cache

* Fixed merge conflict

* Fixed nit wrt to master

* Fixed undeterministic behaviour of Environment.Exit function

* Update timing for terminate process

src/modules/launcher/Wox.Infrastructure/Image/ImageCache.cs

@@ -52,6 +52,16 @@ namespace Wox.Infrastructure.Image
         {
             return _data.Values.Distinct().Count();
         }
+
+        public Dictionary<string, int> GetUsageAsDictionary()
+        {
+            return new Dictionary<string, int>(Usage);
+        }
+
+        public void SetUsageAsDictionary(Dictionary<string, int> usage)
+        {
+            Usage = new ConcurrentDictionary<string, int>(usage);
+        }
     }
 
 }