am: Implement common web applets (#1188)

* am: Implemnet common web applets

This implement parsing of input and output of web applets while making
those close directly.

TODO for the future: Use and hook a web browser.

* Address Ac_K's comments

Ryujinx.HLE/HOS/Applets/Browser/WebExitReason.cs

@@ -0,0 +1,11 @@
+namespace Ryujinx.HLE.HOS.Applets.Browser
+{
+    public enum WebExitReason : uint
+    {
+        ExitButton,
+        BackButton,
+        Requested,
+        LastUrl,
+        ErrorDialog = 7
+    }
+}