[Lightnet] Better errors handling

[shimkiv]

Even though we have the --debug option to print the underlying commands execution stdout/stderr, it will be much better to explain what went wrong to the end used upon their first failure to not ask them repeat such commands again. Alongside with the error message we also need to print the underlying commands used.
For example, if zk lightnet start fails it will be good to see the exact docker run command in use as well as the actual failure reason (resources issues, ports already in use, etc.).

[shimkiv]

Detect ports unavailability and notify users accordingly. Or make it run on any random ports available.

[shimkiv]

Detect resources issues (not enough RAM, CPU, Disk Space).