Implement contact tracing

[paulbessell]

For each person we require a method of logging each infection challenge (sccessful or unsucessful). I suspect a Contact Class to record each contact this will record the duration of each contact and the person that the contact was with.

Once a Covid infected person is symptomatic (cVirus.getIsSymptomatic()) and is test positive (see previous issue) then the people that they were in contact with are traced and isolated if necessary.

This requires some parameters:

1. A default parameter that somebody will comply wiht isolation (same as Implement household isolation parameter)
2. A default parameter that somebody will be available for tracing contacts default 50% and is assigned to the person as an instance variable. Only contacts with adults and Pentioners are traced. We can only trace contacts formt hose that contactTracing == true.
3. We need a default number of one-hour challenges (default 14 over a 5 day period) in order to go into isolation.

[github-actions[bot]]

Heads up @paulbessell @johnnonweiler @vinopm - the "Covid_Simulation_Model" label was applied to this issue.