fix(filmstrip): do not apply flex on local video for horizontal mode

Firefox flex behaves differently from chrome. In firefox, flex
is not allowing the local video and invite button to exceed
the height of the parent, causing the local video to display
shorter than expected due to the invite button. Flex doesn't
need to be applied for local video in horizontal filmstrip
mode as it's only needed in vertical filmstrip mode to
flip the position of the invite button from above the local
video to below. Honestly, this could be better off done
declaratively in the html, but that's not as straigtforward
in this jquery+react world.

css/_filmstrip.scss

          */
         &#filmstripLocalVideo {
             bottom: 32px;
-            flex-direction: column;
+            display: block;
 
             /**
              * The invite button style.

css/_vertical_filmstrip_overrides.scss

          */
         #filmstripLocalVideo {
             bottom: 5px;
+            display: flex;
             flex-direction: column-reverse;
             height: auto;
             justify-content: flex-start;