fix: Update timezone on the interim create page (ietf-tools#4262)

* Fix: Update timezone on the interim create page

The interim creation screen will set the timezone to the timezone of
the browser.  Unfortunately, the UI element was never refreshed, so
it remained on its loaded default, thus telling the user the wrong
value.

This change adds a timezone widget refresh to the end of the function that
loads the browser's local timezone into the timezone value.

This change also adds code to update the 'Local timezone' help text
for the start time and end time input bozes to
call out the selected timezone specifically.

Fixes ietf-tools#3898

* Fix: Change var to const for code review

Author: meadmaker

ietf/static/js/meeting-interim-request.js

@@ -185,6 +185,8 @@ const interimRequest = (function() {
                     .length > 0) {
                     $('#id_time_zone')
                         .val(tzname);
+                    $('#id_time_zone')
+                        .trigger('change');
                 }
             }
         },
@@ -231,10 +233,14 @@ const interimRequest = (function() {
         },
 
         timezoneChange: function () {
+            const tzname = $(this).val();
             $("input[name$='-time']")
                 .trigger('blur');
             $("input[name$='-end_time']")
                 .trigger('change');
+            $('input[type="text"][name*="time"]').next().each(function(){
+                this.innerText = "Time in the " + tzname + " time zone";
+            });
         },
 
         toggleLocation: function () {
@@ -268,4 +274,4 @@ const interimRequest = (function() {
 $(function () {
     'use strict';
     $('#interim-request-form').each(interimRequest.init);
-});
+});