[Modern UI] Refactor and Add Tests for Entrypoints

[andrewbaldwin44]

Proposal

We shouldn't change code to fit the tests, however we should write code in such a way that it is easily testable. After some thought, I concluded that the 'App' file wasn't really rendering the App, but rather a piece of the App. Additionally the 'index' file was doing a lot more than is should be doing, and in this way some important app logic could not be tested.

This PR:

• Moves the logic that was previously defined in the 'index' entrypoint to the 'App' file
• Defines a new folder 'pages', which describes the 3 different parts of the frontend that we have; Dashboard Page, Auth Page, and the HTML Report
• Adds tests for the App and for all three pages
• Adds a test for the FallbackRender

I also ensured in the backend that we have test coverage for:

• Receiving the Dashboard when expected
• Receiving the Auth page when expected
• Receiving the HTML Report when expected

[cyberw]

Sounds reasonable to me.

I suspect the changing of logo.png back to lower resolution is accidental though?