overlays: Add popovers.hide_all call to close_overlay.

This is a prep commit for changing the bots list page to show
normal user popover instead of extended profile one.
This is added so that any open popovers are closed, if one
tries to close the overlay.

This was not needed previously because we were using modal for
showing extended user profile. Now as we would be adding popover,
we would need this to close the open popovers before closing overlay.

static/js/overlays.js

@@ -141,6 +141,8 @@ exports.open_modal = function (selector) {
 };
 
 exports.close_overlay = function (name) {
+    popovers.hide_all();
+
     if (name !== open_overlay_name) {
         blueslip.error("Trying to close " + name + " when " + open_overlay_name + " is open.");
         return;