Add verification state to package file registry

In preparation for reusing the `::Geo::VerificationState` concern.

ee/changelogs/unreleased/mk-secondary-side-verification.yml

+---
+title: 'Geo: Add verification state fields to package file registry'
+merge_request: 49737
+author:
+type: other

ee/db/geo/migrate/20201208025254_add_verification_fields_to_package_file_registry.rb

+# frozen_string_literal: true
+
+class AddVerificationFieldsToPackageFileRegistry < ActiveRecord::Migration[6.0]
+  DOWNTIME = false
+
+  def change
+    add_column :package_file_registry, :verification_state, :integer, default: 0, limit: 2, null: false
+    add_column :package_file_registry, :verification_started_at, :datetime_with_timezone
+  end
+end

ee/db/geo/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 2020_09_24_184638) do
+ActiveRecord::Schema.define(version: 2020_12_08_025254) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
@@ -119,6 +119,8 @@ ActiveRecord::Schema.define(version: 2020_09_24_184638) do
     t.integer "verification_retry_count"
     t.datetime_with_timezone "verified_at"
     t.datetime_with_timezone "verification_retry_at"
+    t.integer "verification_state", limit: 2, default: 0, null: false
+    t.datetime_with_timezone "verification_started_at"
     t.index ["package_file_id"], name: "index_package_file_registry_on_repository_id"
     t.index ["retry_at"], name: "index_package_file_registry_on_retry_at"
     t.index ["state"], name: "index_package_file_registry_on_state"