[FIX] mail: add emoji popover max width

Emoji popover should be rather narrow, it doesn't look good to have one line
of emojis taking the whole screen. The goal is too keep the choices in close
range of the open button for quick selection.

Part of task-2270731

X-original-commit: 75d742f4e48c836f74bc7beee10c89ea544173eb

addons/mail/static/src/components/emojis_popover/emojis_popover.scss

@@ -5,6 +5,7 @@
 .o_EmojisPopover {
     display: flex;
     flex-flow: row wrap;
+    max-width: 200px;
 }
 
 .o_EmojisPopover_emoji {