Changed close buttons of banner and other leaflet sidebars to Bootstrap

app/assets/javascripts/leaflet.share.js

@@ -25,9 +25,8 @@ L.OSM.share = function (options) {
       .attr("class", "sidebar_heading")
       .appendTo($ui)
       .append(
-        $("<span>")
-          .text(I18n.t("javascripts.close"))
-          .attr("class", "icon close")
+        $("<button type='button' class='btn-close float-end mt-1'>")
+          .attr("aria-label",I18n.t("javascripts.close"))
           .bind("click", toggle))
       .append(
         $("<h4>")