kcms/runners: Add option to set whether to open KRunner when typing on desktop

CCBUG: 318538

kcms/runners/krunnersettings.kcfg

@@ -9,6 +9,10 @@
       <label></label>
       <default>false</default>
     </entry>
+    <entry name="activateWhenTypingOnDesktop" key="ActivateWhenTypingOnDesktop" type="Bool">
+      <label></label>
+      <default>true</default>
+    </entry>
     <entry name="retainPriorSearch" key="RetainPriorSearch" type="Bool">
       <label></label>
       <default>true</default>