create a reliable way to get current window url link

[kllarena07]

Is your feature request related to a problem? Please describe. YouTube uses shallow routing so our current method of using load event listener doesn't work reliably whenever the video changes. Tthe popstate and hashchange events do not work as well

Describe the solution you'd like Use a background script to send the current tab url to the content script, which will use the fetch() api to send the video_id to the Flask server. Make sure that this background script also only runs when the tab is on a YouTube video

Describe alternatives you've considered

• Implement this in the Flask server using Starlette
• Have the background script send the video_id directly to the Flask server and return that information to the content script so that the process is not client-sided

[kllarena07]

Additional things to consider

• Test what will happen if multiple windows are running
• Test that data is not slowing down the application
• Make sure that the whole process isn't running if there are dormant or inactive tabs

[vanshb03]

Additional things to consider

• How do we deal with variability in resetting our globalVar?