fix(chat): update thumbs emoji strings

react-emoji-renderer 1.0.0 removed the
thumbsup and thumbsdown aliases.

react/features/chat/smileys.js

@@ -2,14 +2,14 @@ export const smileys = {
     smiley1: ':)',
     smiley2: ':(',
     smiley3: ':D',
-    smiley4: ':thumbsup:',
+    smiley4: ':+1:',
     smiley5: ':P',
     smiley6: ':wave:',
     smiley7: ':blush:',
     smiley8: ':slightly_smiling_face:',
     smiley9: ':scream:',
     smiley10: ':*',
-    smiley11: ':thumbsdown:',
+    smiley11: ':-1:',
     smiley12: ':mag:',
     smiley13: ':heart:',
     smiley14: ':innocent:',