Adding image for debugging and traffic shaping

[vitarb]

Description, Motivation and Context

Finding flaky tests that rely on faulty timing assumptions and fast server performance is tricky. Doing it efficiently requires adding artificial delay for server calls. This PR provides ability to start a version of temporal that induces delay for all network calls by introducing TEMPORAL_DBG_NETWORK_DELAY_MS variable. Treat this as a starting point, we can iterate on top and add a lot more knobs in the future, for adding packet loss, random lags and database delays and some useful debug tools. For now this is targeted primarily for finding flaky tests in our SDKs.
This PR is a refinement of a previous change docker-compose.

Details

To achieve this goal I've used a tool called tc, which is a part of iproute2 package. I didn't want to add iproute2 into our main docker image, since it's needed only for testing, that's why I've created a separate testing/Dockerfile that builds temporal image with any test packages needed for debugging and resiliancy testing, also this image runs a configuration script, before starting the server, which actually invokes tc tool.

Running

docker run -e TEMPORAL_DBG_NETWORK_DELAY_MS=50 --cap-add=NET_ADMIN <container-id>