feat: shorten public urls, add public persistent sharing link API

[agritheory]

Closes #14 and #15

[agritheory]

@Alchez Rohan - json_diff is failing because I added a new custom field. I would love to figure out how to make the action have some sort of "I approve of this difference"

[Alchez]

@agritheory, so there's a couple things to do here for the json diff linter:

• Rob's code manually triggers a sys.exit(1) any time a difference is found. This will need to be removed so that it's only logging the output instead.
• We can add a manual approval step for just the json_diff job:
  • For public repositories, Github recommends using Environments to perform manual approvals.
  • For private repositories, you need to be on Github Pro, Team or Enterprise to use Environments, but there's a community action workflow that uses issues instead to manage the approval process.

The native Github environment workflow seems like it'll require approval before the job runs, rather than after? So maybe we can have the community workflow as a separate step after the output is ready.