Header or Dashboard

[caris-mu]

Is your feature request related to a problem? Please describe.
Related to Issue #101 Header should not be visible when logged out.
Now Header is in the App component, which is shown on every page.

Describe the solution you'd like
Two solutions are:

1. Keep it in App.tsx and hide it on some pages such as login, signup
2. Create a new page called Dashboard which works as a console. Projects and the individual project can be imported to this page so that the user can manage them without jumping to another page.

Short demo

[hunterhector]

Probably hide the pages will create minimum changes to the current project design. We can go that way now. The idea of dashboard is a mixture of the "All Projects" page, the "App" page, and the Header. This involves many steps and probably should be broken down into multiple smaller issues.