Add custom bangs for users

[itsmokha]

Summary

There are many sites that are not eligible for bangs (like, work-related sites, regional sites etc). It would be nice to have an option to allow custom bangs for users.

Motivation

This feature will allow users to have custom bangs, and region specific bangs as well. For example, !a redirects to the US page of amazon, which is not necessarily the region that the users may want to access. If there is an option for custom sites/editing the current bangs, it would be very useful. Currently there are a few extensions on Firefox that do this such as Custom Bang Search and !Bang Quick Search, but it would be very nice to have them all in one extension.

Additional context

• Priority: Nice to have
• Impact: All users can benefit from this