added discord rpc (#1178)

* added discord rpc

* linting issues

* Revert "linting issues"

This reverts commit 55f4e39506.

* fix clang-format issues

* removed wrong rpc submodule

* added correct rpc submodule

* Moved cmake instructions to correct files.

* added minor suggestions from pr

* Added an option to enable/disable RPC, added rpc to emulator.cpp making it work on nonqt builds

* typo & minor stuff

* Changed getInstance implementation with Singleton class.

* Update discord_rpc_handler.cpp

discord id

* fixed ci clangformat errors

---------

Co-authored-by: georgemoralis <giorgosmrls@gmail.com>

src/qt_gui/settings_dialog.ui

@@ -148,6 +148,13 @@
                    </property>
                   </widget>
                  </item>
+                 <item>
+                  <widget class="QCheckBox" name="discordRPCCheckbox">
+                   <property name="text">
+                    <string>Enable Discord Rich Presence</string>
+                   </property>
+                  </widget>
+                 </item>
                 </layout>
                </item>
                <item>