feat: Create flow model and graphQL mutation

packages/backend/src/db/migrations/20211122140336_create_flows.ts

@@ -0,0 +1,15 @@
+import { Knex } from "knex";
+
+export async function up(knex: Knex): Promise<void> {
+  return knex.schema.createTable('flows', (table) => {
+    table.increments('id');
+    table.string('name');
+    table.integer('user_id').references('id').inTable('users');
+
+    table.timestamps(true, true);
+  });
+};
+
+export async function down(knex: Knex): Promise<void> {
+  return knex.schema.dropTable('flows');
+}

packages/backend/src/db/migrations/20211122140612_add_flow_id_to_steps.ts

@@ -0,0 +1,17 @@
+import { Knex } from "knex";
+
+export async function up(knex: Knex): Promise<void> {
+  return knex.schema.table('steps', (table) => {
+    table
+      .integer('flow_id')
+      .references('id')
+      .inTable('flows');
+  });
+}
+
+
+export async function down(knex: Knex): Promise<void> {
+  return knex.schema.table('steps', (table) => {
+    table.dropColumn('flow_id');
+  });
+}