Feature request: Add parser API GW v1 proxy schema & envelope

[ran-isenberg]

This schema exists in the validator but not in the parser. It was requested in the webinar audience.
This feature will also provide an envelope class which will parse the string body parameter as a pydantic Model.

Also added new identity parameters as defined at https://docs.aws.amazon.com/apigateway/latest/developerguide/http-api-develop-integrations-lambda.html

[ran-isenberg]

@heitorlessa i think we can close this issue.

[heitorlessa]

@heitorlessa i think we can close this issue.

I'm leaving them opened and tagged as staged next release ;-)

I'll close it on 1.15.0 release next week

[heitorlessa]

This is now out as part of 1.15.0!!! Thanks a lot again for the contribution ;)

#423