FEATURE: Support backup uploads/downloads directly to/from S3.

This reverts commit 3c59106bac.

app/models/backup_location_site_setting.rb

@@ -0,0 +1,23 @@
+# frozen_string_literal: true
+
+require_dependency 'enum_site_setting';
+
+class BackupLocationSiteSetting < EnumSiteSetting
+  LOCAL ||= "local"
+  S3 ||= "s3"
+
+  def self.valid_value?(val)
+    values.any? { |v| v[:value] == val }
+  end
+
+  def self.values
+    @values ||= [
+      { name: "admin.backups.location.local", value: LOCAL },
+      { name: "admin.backups.location.s3", value: S3 }
+    ]
+  end
+
+  def self.translate_names?
+    true
+  end
+end