networks: Implement wizard steps for selecting FreedomBox Internet connectivity

Currently when setting up FreedomBox, we are not guiding users on how to setup their domains or how to configure their router. We have a UX design plan for changing this. One of the parts of this plan is to ask the user for how their FreedomBox is connected to the Internet. We store this information and use it suggest various setup options during the setup process and also later on when setting up apps. Implement asking for how FreedomBox is connected to the Internet. See page number 1 of reachability UX (#1531).

• Implement a form in networks/forms.py for asking how the FreedomBox is connected to the Internet. The three options provided and their descriptions should be show in the UX design.
• Implement a simple page view to show this in networks/views.py and add the view to networks/urls.py. This page should be independent and should not contain distractions like app header etc. See Gitweb's create repro view as an example. Ignore showing the diagrams from the UX design for the purpose of this task.
• Add a new section in the Networks main page with section title 'FreedomBox Internet Connectivity' and a button to link to the newly created page. See page 18 of the reachability UX (#1531). Again, ignore the diagram.
• Create another view that reuses the form created earlier but appears like a wizard step. See page 1 of the reachability UX (#1531). See users/views.py::FirstBootView as an example. 'Skip' and 'Next' need to be implemented.
• Declare a first boot step that will show up as part of the first boot wizard that appears during initial FreedomBox setup. See users/init.py::first_boot_steps for example on how to do this. We currently have to wizard three wizard steps Welcome (order 0), User Account Creation (order 1) and Finish (order 10). Insert our first boot wizard step with order 2.
• When the form is submitted in both cases (from networks app or from first boot wizard), Store this information in sqlite database against a key named 'networks_connection_type' in FreedomBox's key/value store. Values can be one of 'to_router', 'as_router' and 'direct'. See config/init.py::set_advanced_mode() for example on how to store the key.

This task is nominated for 'Contributor Invite' (ping @dannyhaidar-guest):

• Effort Area: Coding
• Effort Estimate: 4/5
• Skills Required: Python, Django forms/views/urls/templates