Keyboard Access On Handin Page and PLD/GDU Tooltip

[xinyis991105]

Description

This PR improves keyboard access for Autolab. Specifically, if users wish to, they can now access the handin dragin box on assessment handin page and the tooltip information for PLD/GDU on gradebook page.

Motivation and Context

This is advised by Perkins as they see the need to make Autolab a good experience for keyboard users as well.

How Has This Been Tested?

1. Go to any assessment's handin page and press the Tab key to navigate through the page. You should be able to focus on the handin box at a certain point. Hitting enter when the focus is on the handin box will pop up the file selection window.
2. Go to the Gradebook page as a student and press the Tab key to navigate. You should be able to focus on the PLD/GDU icons with the tooltip displaying information automatically.

Screenshots (if appropriate):

(Hard to see but the mouse is not being hovered over the two areas.)

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My change requires a change to the documentation, which is located at Autolab Docs
• I have updated the documentation accordingly, and here is the corresponding pull request to Autolab Docs ->

Other issues / help required

If unsure, feel free to submit first and we'll help you along.