implement integration test scaffolding

[willkg]

Implement integration test scaffolding for supporting sentry clients. For starters:

• python sentry-sdk

[willkg]

It'd be nice to do this with an integration test. You run Kent and then run the integration test which uses the various supported clients and client versions. They emit an event, then pull the event from Kent and verify it using the list API.

I'm going to rescope this to "implement integration test scaffolding". Initially, it can test with a few versions of Python sentry-sdk.