101 featch available variables from previous steps (#8062)

- add outputSchema in workflow step settings
- use outputSchemas to compute step available variables


https://github.com/user-attachments/assets/6b851d8e-625c-49ff-b29c-074cd86cbfee

packages/twenty-front/src/modules/workflow/hooks/useComputeStepOutputSchema.ts

@@ -0,0 +1,26 @@
+import { useApolloMetadataClient } from '@/object-metadata/hooks/useApolloMetadataClient';
+import { ApolloClient, useMutation } from '@apollo/client';
+import {
+  ComputeStepOutputSchemaInput,
+  ComputeStepOutputSchemaMutation,
+  ComputeStepOutputSchemaMutationVariables,
+} from '~/generated/graphql';
+import { COMPUTE_STEP_OUTPUT_SCHEMA } from '@/workflow/graphql/mutations/computeStepOutputSchema';
+
+export const useComputeStepOutputSchema = () => {
+  const apolloMetadataClient = useApolloMetadataClient();
+  const [mutate] = useMutation<
+    ComputeStepOutputSchemaMutation,
+    ComputeStepOutputSchemaMutationVariables
+  >(COMPUTE_STEP_OUTPUT_SCHEMA, {
+    client: apolloMetadataClient ?? ({} as ApolloClient<any>),
+  });
+
+  const computeStepOutputSchema = async (
+    input: ComputeStepOutputSchemaInput,
+  ) => {
+    return await mutate({ variables: { input } });
+  };
+
+  return { computeStepOutputSchema };
+};