feat: support for synchronous custom step handling

[WilliamBergamin]

Summary

This PR changes the way function_executed events handle auto acknowledgement. These changes lift the auto ack logic into a middleware that is then registered to the function listener.

The function listener exposes an autoAcknowledge flag, when enabled (default) the auto ack middleware is added, when disabled the auto ack middleware is not added. This allows the function listener to support dynamic options use cases, functions used as dynamic inputs must complete or fail before acknowledging the request (this provides a crisp user experience).

Example

app.function('get-options', { autoAcknowledge: false }, async ({ inputs, ack, fail, complete }) => {
  try {
    const category: string[] = inputs.category as string[];
    if (category.includes('dogs')) {
      complete({
        outputs: {
          options: [
            { key: 'Poodle', value: 'value-0' },
            { key: 'Bulldog', value: 'value-1' },
            { key: 'Beagle', value: 'value-2' },
          ],
        },
      });
    } else if (category.includes('cars')) {
      complete({
        outputs: {
          options: [
            { key: 'Toyota', value: 'value-0' },
            { key: 'Ford', value: 'value-1' },
            { key: 'Jeep', value: 'value-2' },
          ],
        },
      });
    } else {
      fail({ error: `Invalid category: ${category} (valid: 'dogs', 'cars')` });
    }
  } catch (error) {
    fail({ error: `Failed to handle a function request (error: ${error})` });
  } finally {
    await ack();
  }
});

Manual tests

These changes were manually tested against

• bolt-js-custom-step-template -> no breaking change observed
• bolt-ts-starter-template -> no breaking change observed

Testing

1. Pull this branch
2. npm install & npm run build
3. Use npm install path/to/the/bolt-js/project to install the built package in a project with a custom step like bolt-js-custom-step-template
4. Set the options field of the function handler to { autoAcknowledge: false }
5. You should now be able to use the ack input parameter in your handler
6. AutoAck behavior is now disabled you must now manually call await ack(); for this specfic handler

Requirements (place an x in each [ ])

• I've read and understood the Contributing Guidelines and have done my best effort to follow them.
• I've read and agree to the Code of Conduct.