[FEATURE] Add Firefox Beta & Nightly to Search Bar

Describe the feature

Currently, in the search bar configuration you can select Firefox, Ironfox, Google etc but not the beta version of Firefox. What I'm suggesting is to add both the nightly and beta versions of Firefox to the search menu

Why would it be useful to add?

Because currently, we have to select I.e duckduckgo as a website for the search bar to function, instead of going to the built in search bar.

Did the feature exist in Lawnchair Legacy?

No

Example(s)

N/A

Additional context

I'm willing to beta test or help code this feature if needed