Improving tests env

[smallhive]

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

A new tests run env is good and it can be better after some quality of live updates.

Describe the solution you'd like

As a developer I need options to use my own s3-gate. Just replace a separate binary file is good but if I need to replace gate file I have to restart all env. This way is not suggesting a way to propper debug routine.
The best solution is generating the complete s3 gate config file. I mean I would use this file as a parameter to the gate --config /some/path/to/config.yaml
Right now I tried to use configuration file, but was failed. Some parameters, like node-peears are set via env params and I can't find them.

Running tests generate tons of rows. It is difficult to find info. We may group all useful data (paths to configs, to logs, etc) in one place or maybe use green or any colour to highlight it in logs.

Describe alternatives you've considered

Improve test logging and make them configurable in some way. Reducing logs may be also good option

Additional context

Right now maybe not very actual, but the same would be useful for the REST gate as well.