feat(extension): show list of all downloads in popup

[jordanshatford]

Describe the problem

Right now the popup will only show information for the download if the tab is a valid YouTube video and the video is being downloaded.

Describe the proposed solution

We should have a list of all downloads active in the background at the time of opening the popup. This could be a tab in the popup so that the main information is still for the current tab.

Alternatives considered

N/A

Importance

nice to have

Additional information

N/A