feat: Add a pre-chat form on widget (#1769)

db/migrate/20210212154240_add_request_for_email_on_channel_web_widget.rb

@@ -0,0 +1,15 @@
+class AddRequestForEmailOnChannelWebWidget < ActiveRecord::Migration[6.0]
+  def up
+    change_table :channel_web_widgets, bulk: true do |t|
+      t.column :pre_chat_form_enabled, :boolean, default: false
+      t.column :pre_chat_form_options, :jsonb, default: {}
+    end
+  end
+
+  def down
+    change_table :channel_web_widgets, bulk: true do |t|
+      t.remove :pre_chat_form_enabled
+      t.remove :pre_chat_form_options
+    end
+  end
+end