Add "browse all fields" page

[hobofan]

Right now the way to browse all fields is done via listing all fields on the index page under the "recently updated" section, which won't be tractable in the long-term as the amount of fields in the registry grows.

Instead, there should be a dedicated page that allows for browsing all packages in a paginated manner (and restricting the "recently updated" section to the ~20 latest)