Allow setting HTTP listen address and TCP port

[helmut72]

Is your feature request related to a problem? Please describe.

Using watchtower in network_mode: host, it always bind to TCP port 8080 and listen on every network interface *:8080 (LISTEN).

Describe the solution you'd like

An option like HTTP_API_LISTEN=127.0.0.1:1234 would be great.

Describe alternatives you've considered

Create a network for this single instance and map a different TCP port.

Additional context

Thank you

[github-actions]

Hi there! 👋🏼 As you're new to this repo, we'd like to suggest that you read our code of conduct as well as our contribution guidelines. Thanks a bunch for opening your first issue! 🙏