Add automatic room sidebar hiding option

Add menu option to change whether the room information drawer is opened automatically or not. This also adds some code to switch off the dim effect during the first animation after modal is changed as this looked bad.

Implements network/neochat#243

Slight cleanup removing the edge option for context drawer from main.qml as this is duplicated from RoomDrawer.qml

src/neochatconfig.kcfg

@@ -54,6 +54,10 @@
     <entry name="TypingNotifications" type="bool">
       <default>true</default>
     </entry>
+    <entry name="AutoRoomInfoDrawer" type="bool">
+      <label>Automatic Hide/Unhide Room Information</label>
+      <default>true</default>
+    </entry>
   </group>
   <group name="Timeline">
     <entry name="ShowAvatarInTimeline" type="bool">