Introduce Cloud License related GraphQL types

doc/api/graphql/reference/index.md

ee/app/graphql/ee/types/query_type.rb

...esolvers/admin/cloud_licenses/current_license_resolver.rb

.../admin/cloud_licenses/license_history_entries_resolver.rb

...raphql/types/admin/cloud_licenses/current_license_type.rb

.../types/admin/cloud_licenses/license_history_entry_type.rb

ee/app/graphql/types/admin/cloud_licenses/license_type.rb

ee/app/models/license.rb

...ers/admin/cloud_licenses/current_license_resolver_spec.rb

...n/cloud_licenses/license_history_entries_resolver_spec.rb

...l/types/admin/cloud_licenses/current_license_type_spec.rb

...s/admin/cloud_licenses/license_history_entry_type_spec.rb

ee/spec/graphql/types/query_type_spec.rb

ee/spec/models/license_spec.rb

...ypes/admin/cloud_licenses/license_type_shared_examples.rb