Added navigation

[SciGuyTy]

Description

This PR implements a navigation system using react router for the admin dashboard.

To add a new navigation item in the navigation menu, simply insert a new 'route object' in the routes array found in src/routes/Dashboard/Dashboard.jsx. The 'route object' is defined as follows:

{
   icon: React.Component
   label: String
   route: String
}

Additionally, you will need to add a new child component in the the 'routes' array in index.js. Details on the structure of these route objects can be found in the react router documentaiton.