Add a nodeinfo endpoint (#12002)

* Add nodeinfo endpoint

* dont commit stuff from my local dev

* consistant naming since we implimented 2.1 schema

* Add some additional node info stuff

* Add nodeinfo endpoint

* dont commit stuff from my local dev

* consistant naming since we implimented 2.1 schema

* expanding this to include federation info

* codeclimate feedback

* CC feedback

* using activeserializers seems like a good idea...

* get rid of draft 2.1 version

* Reimplement 2.1, also fix metaData -> metadata

* Fix metaData -> metadata here too

* Fix nodeinfo 2.1 tests

* Implement cache for monthly user aggregate

* Useless

* Remove ostatus from the list of supported protocols

* Fix nodeinfo's open_registration reading obsolete setting variable

* Only serialize domain blocks with user-facing limitations

* Do not needlessly list noop severity in nodeinfo

* Only serialize domain blocks info in nodeinfo when they are set to be displayed to everyone

* Enable caching for nodeinfo endpoints

* Fix rendering nodeinfo

* CodeClimate fixes

* Please CodeClimate

* Change InstancePresenter#active_user_count_months for clarity

* Refactor NodeInfoSerializer#metadata

* Remove nodeinfo 2.1 support as the schema doesn't exist

* Clean-up

spec/controllers/well_known/nodeinfo_controller_spec.rb

@@ -0,0 +1,36 @@
+require 'rails_helper'
+
+describe WellKnown::NodeInfoController, type: :controller do
+  render_views
+
+  describe 'GET #index' do
+    it 'returns json document pointing to node info' do
+      get :index
+
+      expect(response).to have_http_status(200)
+      expect(response.content_type).to eq 'application/json'
+
+      json = body_as_json
+
+      expect(json[:links]).to be_an Array
+      expect(json[:links][0][:rel]).to eq 'http://nodeinfo.diaspora.software/ns/schema/2.0'
+      expect(json[:links][0][:href]).to include 'nodeinfo/2.0'
+    end
+  end
+
+  describe 'GET #show' do
+    it 'returns json document with node info properties' do
+      get :show
+
+      expect(response).to have_http_status(200)
+      expect(response.content_type).to eq 'application/json'
+
+      json = body_as_json
+
+      expect(json[:version]).to eq '2.0'
+      expect(json[:usage]).to be_a Hash
+      expect(json[:software]).to be_a Hash
+      expect(json[:protocols]).to be_an Array
+    end
+  end
+end