feat!: update to latest version of clouevents sdk

[matthewrobertson]

This commit updates to the latest CESDK which provides a generic interface for CloudEvents. This is an additive, non-breaking change to our registration API:

providing a template type on the registration function:

import * as functions from '@google-cloud/functions-framework';

functions.cloudEvent<string>('helloTypes', (ce) => {
  // the event data is strongly typed here
  ce.data.length;
});

providing a template type on the argument annotation:

import {CloudEvent}, * as functions from '@google-cloud/functions-framework';

functions.cloudEvent('helloTypes', (ce: CloudEvent<string>) => {
  // the event data is strongly typed here
  ce.data.length;
});

not providing a template is still allowed:

import functions from '@google-cloud/functions-framework';

functions.cloudEvent('helloTypes', (ce) => {
  // the event data has type "unknown" by default so the customer can cast to anything they want 
  const data = ce.data as string;
  data.length; // OK
});

[grant]

Awesome! This is the ideal experience I've been looking for with event types.

Had a couple comments, mainly for making sure this is tested.

[grant]

Looks pretty good. Are we able to test with an unparameterized CloudEvent to preserve the existing test?

LGTM after requested changes.

[grant]

Thanks. I think there might be a push that is missing.

[grant]

LGTM!

[grant]

It would be a little funky requiring a unknown here. Question:

• functions.CloudEvent (can we do this?)
• functions.CloudEvent<unknown>

[grant]

Is it possible for a developer to write a CloudEventFunction without a parameterized type?

Perhaps it is not possible.

export type HandlerFunction<T = unknown> =
  | HttpFunction
  | EventFunction
  | EventFunctionWithCallback
  | CloudEventFunction<T>
  | CloudEventFunctionWithCallback<T>
  | CloudEventFunction
  | CloudEventFunctionWithCallback;