Validate nodeinfo response by schema (#21395)

* add json-schema to :test in Gemfile

* Create node_info_2.0_schema.json

* test match_response_schema

* Create match_response_schema.rb

* Update nodeinfo_controller_spec.rb

* Rename spec/support/node_info_2.0_schema.json to spec/support/schema/node_info_2.0_schema.json

* Update match_response_schema.rb

* cleanup

* additionally validate the json schema itself

disable throwing errors

test the schema matcher

* rename nodeinfo schema to nodeinfo_2.0

* use Rails.root.join to construct the path

* prettify json

* sync Gemfile.lock