Added `Display` class, and several UI features

[colinmatti]

Description

Added functions to the Display class, added a black screen to the UI when the power is off, and mapped the arrow buttons and Power button to their correct functionality. When this PR is merged, you should be able to turn on and off the device and navigate the screens menu.

I also started adding functions to the Device class to allow for past sessions to be added to the data base so that I'm able to display past sessions to the UI. I will continue this at a later PR - shipping this now to unblock.

Fixes # (issue)

Type of change

Please delete options that are not relevant.

• [ ] Bug fix (non-breaking change which fixes an issue)
• [X] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [ ] This change requires a documentation update

How Has This Been Tested?

By me

Checklist:

• [X] My code follows the style guidelines of this project
• [X] I have performed a self-review of my own code
• [X] I have commented my code, particularly in hard-to-understand areas
• [X] I have made corresponding changes to the documentation
• [X] My changes generate no new warnings
• [X] I have added tests that prove my fix is effective or that my feature works
• [X] New and existing unit tests pass locally with my changes
• [X] Any dependent changes have been merged and published in downstream modules

Your life story (for context):

Please write 10-15 paragraphs