Description

Currently a random port is assigned on the host machine side when exposing a port
using the local:docker's exposed_ports argument that can be defined in a testplan's manifest.toml file.

I've looked at the source code before, and it seems a limitation of the docker Go lib we use.

This is however pretty annoying as it means you cannot hardcode anywhere in a dev tool these exposed ports,
as the port that we actual would have to dial to changes each time.

Original motivation for this issue is a kind of browser testplan, where we would like to expose a port to be able to remotely debug a chrome browser running in a docker-driven testplan. The debugging is already possible today, but requires each time to look up the port which was chosen on the host-machine side, in order to be able to connect to it. Having the ability to set that port also manually (e.g. to the same port as the one on the docker side) would help make this dev flow a lot easier.