Add a frontend app

[glenacota]

Develop a frontend for the backend apps. Here is a list of requirements:

• MUST provide a page to display all todos (fetched from the todos app)
• MUST provide a form to create a new todo (stored by the todos app)
• MUST allow to update one todo status per time (updated by the todos app)
• MUST allow to download a PDF summary with all the todos (fetched from the reports app)
• MUST be monitorable by Filebeat and Metricbeat
• MUST be implemented using one of the languages supported by Elastic APM Agent (https://www.elastic.co/guide/en/apm/agent/index.html)
• SHOULD be as lightweight as possible (should be possible to run it on your local machine together with the other apps and the Elastic Stack)
• WOULD-BE-NICE if it makes the management of the todos' id transparent to the user