UI: Add kudos to AppData file

Kudos are read by app centers such as GNOME Software and Discover
to calculate the "awesomeness" level of the application. OBS Studio
qualifies for two of these kudos: the "hi-dpi icon" kudo, since we
have 128x128 and bigger icons; and the "modern toolkit" icon, since
we use Qt5.

Add these kudos to the AppData file, and let app centers tell the
world how awesome OBS Studio is :)

UI/xdg-data/com.obsproject.Studio.appdata.xml.in

@@ -17,6 +17,10 @@
     </screenshot>
   </screenshots>
   <content_rating type="oars-1.1"/>
+  <kudos>
+    <kudo>ModernToolkit</kudo>
+    <kudo>HiDpiIcon</kudo>
+  </kudos>
   <releases>
     <release version="@OBS_VERSION@" date="@APPDATA_RELEASE_DATE@"/>
   </releases>