UI: Include OpenSans font with OBS

Also reinstates the font-family statement removed in 2941c48

UI/data/themes/Yami.qss

@@ -82,6 +82,7 @@ QWidget {
     selection-background-color: rgb(40,76,184);
     selection-color: palette(text);
     font-size: 10pt;
+    font-family: 'Open Sans', Helvetica, Arial, 'MS Shell Dlg', sans-serif
 }
 
 QWidget:disabled {

UI/forms/obs.qrc

@@ -73,4 +73,9 @@
     <file>images/settings/hotkeys.svg</file>
     <file>images/settings/accessibility.svg</file>
   </qresource>
+  <qresource prefix="">
+    <file>fonts/OpenSans-Regular.ttf</file>
+    <file>fonts/OpenSans-Bold.ttf</file>
+    <file>fonts/OpenSans-Italic.ttf</file>
+  </qresource>
 </RCC>

UI/obs-app.cpp

@@ -2191,6 +2191,11 @@ static int run_program(fstream &logFile, int argc, char *argv[])
 	OBSApp program(argc, argv, profilerNameStore.get());
 	try {
 		QAccessible::installFactory(accessibleFactory);
+		QFontDatabase::addApplicationFont(
+			":/fonts/OpenSans-Regular.ttf");
+		QFontDatabase::addApplicationFont(":/fonts/OpenSans-Bold.ttf");
+		QFontDatabase::addApplicationFont(
+			":/fonts/OpenSans-Italic.ttf");
 
 		bool created_log = false;