Add Delivery Settings + improve 'Notify Customers' functionality (#15322)

* Add Delivery Settings + improve 'Notify Customers' functionality

* Minor improvements

* Add patch to create a default dispatch notification template

* Fix travis errors

erpnext/patches/v11_0/add_default_dispatch_notification_template.py

@@ -0,0 +1,25 @@
+import os
+
+import frappe
+from frappe import _
+
+
+def execute():
+	frappe.reload_doc("email", "doctype", "email_template")
+	frappe.reload_doc("stock", "doctype", "delivery_settings")
+
+	if not frappe.db.exists("Email Template", _("Dispatch Notification")):
+		base_path = frappe.get_app_path("erpnext", "stock", "doctype")
+		response = frappe.read_file(os.path.join(base_path, "delivery_trip/dispatch_notification_template.html"))
+
+		frappe.get_doc({
+			"doctype": "Email Template",
+			"name": _("Dispatch Notification"),
+			"response": response,
+			"subject": _("Your order is out for delivery!"),
+			"owner": frappe.session.user,
+		}).insert(ignore_permissions=True)
+
+	delivery_settings = frappe.get_doc("Delivery Settings")
+	delivery_settings.dispatch_template = _("Dispatch Notification")
+	delivery_settings.save()