Minor UI improvements (#7137)

* PLT-7303 - Fixing manage members button

* Revert "PLT-7303 - Fixing manage members button"

This reverts commit 7dcb68a8e333a2c95444d417ed9a244c9c30aa99.

* PLT-7303 - Redesigning channel members popover

* Updating font size and positioning

webapp/i18n/en.json

@@ -1764,7 +1764,7 @@
   "member_list.noUsersAdd": "No users to add.",
   "members_popover.manageMembers": "Manage Members",
   "members_popover.msg": "Message",
-  "members_popover.title": "Members",
+  "members_popover.title": "Channel Members",
   "members_popover.viewMembers": "View Members",
   "mfa.confirm.complete": "<strong>Set up complete!</strong>",
   "mfa.confirm.okay": "Okay",