JSON content parity with AppSpot

[amis92]

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: BattleScribe/Release#148

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

[amis92]

Repositories currently not listed:

• because of pre-release and no latest release:
  https://github.com/BSData/f28
  https://github.com/BSData/infinity
• because of being archived and not battlescribe-data tagged:
  https://github.com/BSData/necromunda
  https://github.com/BSData/super-hero-universe
  https://github.com/BSData/wh40k-shadow-war-armageddon
  https://github.com/BSData/wh40k-8th-edition
  https://github.com/BSData/wh40k-mobile-format
  https://github.com/BSData/wh40k-path-to-glory
  https://github.com/BSData/warhammer-diskwars

Also some (all?) of the above don't have release assets.

[amis92]

Also, we'd need to generate some "aggregate" Atom/RSS release feed that's available at http://battlescribedata.appspot.com/repos/feeds/all.atom