As outlined in a [Swift forums post in November ’21](https://forums.swift.org/t/swiftnio-swift-version-support/53232), SwiftNIO will only support the latest non-patch Swift release and the 2 immediately prior non-patch versions.
In this commit we drop support for Swift 5.2 and 5.3.
motivation: demonstrate how to use events using sample code
changes:
* add basic sample for API Gateway
* add docker setup to test samples when changing events