Contract tests restructure

lib/tasks/contracts.rake

spec/contracts/consumer/endpoints/project/merge_requests.js

...mer/fixtures/project/merge_request/diffs_batch.fixture.js

.../fixtures/project/merge_request/diffs_metadata.fixture.js

...mer/fixtures/project/merge_request/discussions.fixture.js

spec/contracts/consumer/specs/diffs.spec.js

spec/contracts/consumer/specs/discussions.spec.js

spec/contracts/consumer/specs/metadata.spec.js

...ntracts/consumer/specs/project/merge_request/show.spec.js

...mergerequest#show-merge_request_diffs_batch_endpoint.json

...gerequest#show-merge_request_diffs_metadata_endpoint.json

...mergerequest#show-merge_request_discussions_endpoint.json

.../pact_helpers/project/merge_request/diffs_batch_helper.rb

...ct_helpers/project/merge_request/diffs_metadata_helper.rb

.../pact_helpers/project/merge_request/discussions_helper.rb

spec/contracts/provider/specs/diffs_helper.rb

spec/contracts/provider/specs/metadata_helper.rb

...rovider/states/project/merge_request/diffs_batch_state.rb

...ider/states/project/merge_request/diffs_metadata_state.rb

...rovider/states/project/merge_request/discussions_state.rb