`plugins.install`

Downloads a plugin from a GitHub release and adds it.

It fetches releases/tags/<version> and downloads the first asset, which must be a zip with plugin.lua at its root.
The zip is saved as <state_dir>/plugins/<owner>_<repo>_<tag>.zip.
The stored metadata is {"source": "github", "owner", "repository", "version"}, which plugins.upgrade relies on.

Request

{
  "owner": "porla-plugins",
  "repository": "metrics",
  "version": "v0.1",
  "config": "return {}"
}

{
  "id": 8
}

Code	Reason
-2	Release not found
-3	Failed to parse release body as JSON
-4	Release has no downloadable assets
-5	Failed to fetch release asset
-6	Failed to write release archive to `<path>`
-7	Plugin path is used by another plugin