add modal next/prev button to be localized (#5245)

webapp/i18n/en.json

@@ -1306,6 +1306,8 @@
   "filtered_user_list.countTotal": "{count} {count, plural, =0 {0 members} one {member} other {members}} of {total} total",
   "filtered_user_list.countTotalPage": "{startCount, number} - {endCount, number} {count, plural, =0 {0 members} one {member} other {members}} of {total} total",
   "filtered_user_list.member": "Member",
+  "filtered_user_list.next": "Next",
+  "filtered_user_list.prev": "Previous",
   "filtered_user_list.search": "Search users",
   "filtered_user_list.searchButton": "Search",
   "filtered_user_list.show": "Filter:",
@@ -1625,7 +1627,9 @@
   "more_channels.create": "Create New Channel",
   "more_channels.createClick": "Click 'Create New Channel' to make a new one",
   "more_channels.join": "Join",
+  "more_channels.next": "Next",
   "more_channels.noMore": "No more channels to join",
+  "more_channels.prev": "Previous",
   "more_channels.title": "More Channels",
   "more_direct_channels.close": "Close",
   "more_direct_channels.message": "Message",