Port Deepcite to Firefox

[connorjoleary]

Is your feature request related to a problem? Please describe.
In order to hit a larger audience, Deepcite should be available in more places. A good place to start would be with Firefox

Describe the solution you'd like
Be able to run on Firefox browser.

Describe alternatives you've considered
Safari would be another great option, but I believe that apple has strict licensing.

Additional context
This program ran on Firefox in its early stages, so I believe doing it again would be straight forward.

[oaao]

https://www.extensiontest.com/test/2dc58830-87c5-11ec-b699-59b35e8ab6aa

Prelim looks good!