Remove pointless packages and create test for all supported frameworks

[abemedia]

Issue #, if available: n/a

Description of changes:

The majority of packages in this repo are kind of pointless as all those frameworks implement the http.Handler interface.
This PR removes them and instead adds tests to the httpadapter package for each supported framework.

Migration is as simple as replacing the package name.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[sapessi]

This is a major breaking change. We will consider it for a major release of the framework