Add Pinpoint Events

[sollniss]

Is your feature request related to a problem? Please describe.
We are receiving Pinpoint events from Kinesis, but it seems there are no official-ish types for them anywhere except for the documentation below.

• https://docs.aws.amazon.com/pinpoint/latest/developerguide/event-streams-data-journey.html
• https://docs.aws.amazon.com/pinpoint/latest/developerguide/event-streams-data-email.html
• https://docs.aws.amazon.com/pinpoint/latest/developerguide/event-streams-data-sms.html

Describe the solution you'd like
events.PinpointEvent or events.PinpointEmailEvent, events.PinpointSMSEvent, events.PinpointJourneyEvent if they can't be expressed as a single type.

Describe alternatives you've considered
I've looked everywhere for a definition of these events, but haven't found anything yet.
We are currently using custom types to parse these, but it would be nice to have them here, or even better in the SDK itself.

Additional context
Add any other context or screenshots about the feature request here.