JSON content parity with AppSpot

This is to track progress on being able to redirect traffic from AppSpot to Gallery:

## Some repositories aren't included

The following are requirements for a repository to show up in Gallery listing:
- registration in `registry` folder of this repo
- latest release (not pre-release)
- latest release contains assets produced by BSData/publish-catpkg

BSData repos are automatically registered via "Update registry" workflow if they're tagged with `battlescribe-data` GitHub topic.

Latest release has to be published by someone.

Release assets on older repositories can be added "manually" via `/publish-ext` chatops command in `BSData/publish-catpkg` repo.

There are repositories that don't meet all requirements because either:
- they don't have latest release
- they don't have `battlescribe-data` tag

## Timestamps don't show up in BattleScribe

The issue is here: https://github.com/BattleScribe/Release/issues/148

We may want to workaround this because of BS slow update schedule.