Replace bootstrap3-datetimepicker with a BS4 equivalent

Gemfile

@@ -34,7 +34,8 @@ gem 'fog-core'
 gem 'fog-aws'
 gem 'fog-local'
 gem 'momentjs-rails', '>= 2.9.0'
-gem 'bootstrap3-datetimepicker-rails', '~> 4.7.14'
+gem 'moment-timezone-rails', '~> 1.0'
+gem 'bootstrap4-datetime-picker-rails'
 gem 'tiny-color-rails'
 gem 'jquery-minicolors-rails'
 gem 'colorize'

Gemfile.lock

@@ -80,8 +80,10 @@ GEM
       autoprefixer-rails (>= 9.1.0)
       popper_js (>= 1.14.3, < 2)
       sassc-rails (>= 2.0.0)
-    bootstrap3-datetimepicker-rails (4.7.14)
-      momentjs-rails (>= 2.8.1)
+    bootstrap4-datetime-picker-rails (0.3.1)
+      jquery-rails (~> 4.2, >= 4.2.0)
+      moment-timezone-rails (~> 1.0)
+      momentjs-rails (>= 2.10.5, <= 3.0.0)
     bootstrap_form (4.4.0)
       actionpack (>= 5.0)
       activemodel (>= 5.0)
@@ -268,6 +270,8 @@ GEM
     mini_mime (1.0.2)
     mini_portile2 (2.4.0)
     minitest (5.14.0)
+    moment-timezone-rails (1.0.0)
+      momentjs-rails (>= 2.10.5, <= 3.0.0)
     momentjs-rails (2.20.1)
       railties (>= 3.1)
     multi_json (1.14.1)
@@ -512,7 +516,7 @@ DEPENDENCIES
   bcrypt (~> 3.1.7)
   better_errors
   bootstrap (~> 4.4, >= 4.4.1)
-  bootstrap3-datetimepicker-rails (~> 4.7.14)
+  bootstrap4-datetime-picker-rails
   bootstrap_form
   brakeman
   byebug
@@ -542,6 +546,7 @@ DEPENDENCIES
   jquery-rails
   jquery-turbolinks
   letter_opener
+  moment-timezone-rails (~> 1.0)
   momentjs-rails (>= 2.9.0)
   newrelic_rpm
   nprogress-rails

app/assets/javascripts/moderation.js.erb.coffee

@@ -1,3 +1,5 @@
 #= require moment
-#= require bootstrap-datetimepicker
+#= require tempusdominus-bootstrap-4
 #= require_tree ./moderation
+
+$('.datetimepicker-input').datetimepicker();

app/assets/stylesheets/application.scss

@@ -26,7 +26,7 @@
 
 @import
 "bootstrap",
-"bootstrap-datetimepicker",
+"tempusdominus-bootstrap-4",
 "font-awesome",
 "nprogress",
 "nprogress-bootstrap";
@@ -76,6 +76,7 @@
  */
 
 @import
+"components/announcements",
 "components/answerbox",
 "components/avatars",
 "components/buttons",