Store arbitrary context in Flow AsyncLocalStorage

[mbleigh]

Because tools and flows are defined independently but are often interrelated in practice, it would be great to be able to set and retrieve arbitrary values from ALS. Something like:

import { setFlowContext, getFlowContext, defineFlow, defineTool, generate } from "genkit";

const findRestaurant = defineTool({
  name: 'findRestaurant',
  inputSchema: z.object({query: z.string()}),
  async ({query}) => {
    const userInfo = getFlowContext('userInfo');
    return searchRestaurants(query, zipcode: userInfo.zipcode);
  }
});

defineFlow({
  name: 'chatbotFlow',
  inputSchema: z.object({userInfo: UserInfoSchema}),
}, ({userInfo}) => {
  setFlowContext('userInfo', userInfo);
  generate({
    // ...
    tools: [findRestaurant],
  });
});