Merge branch 'block-behavior' into 'develop'

Configurable block visibility, fixes #2123

Closes #2123

See merge request pleroma/pleroma!3242

config/description.exs

@@ -1670,6 +1670,11 @@ config :pleroma, :config_description, [
         type: :boolean,
         description: "Whether to federate blocks to other instances"
       },
+      %{
+        key: :blockers_visible,
+        type: :boolean,
+        description: "Whether a user can see someone who has blocked them"
+      },
       %{
         key: :sign_object_fetches,
         type: :boolean,