Feature/683 resolve hostname from first network

[HofmeisterAn]

What does this PR do?

Changes the container hostname resolution. The previous implementation only considers networks with the name bridge.

Why is it important?

If developers run in a Docker Wormhole environment, and assign a custom network, the previous implementation returned a wrong hostname. It did not consider the custom network. Custom networks cannot use the name bridge, it is a reserved name.

The fallback to NetworkSettings.Gateway does not make sense:

Deprecated: This field is only propagated when attached to the default "bridge" network. Use the information from the "bridge" network inside the Networks map instead, which contains the same information. This field was deprecated in Docker 1.9 and is scheduled to be removed in Docker 17.12.0

Related issues

• Relates Azure Pipeline - Communication TCP between tests and containers with TCP Server #679
• Closes Running container inside container with custom network returns wrong gateway address #683

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