enable autopeering via environmental variable

[0pcom]

The reasoning behind this PR is that I was unable to successfully modify the systemd service for skywire via a drop-in override configuration file to change ExecStart to include the -m flag for enabling the autopeering ; nor was I able to render an env in ExecStart to provide the -m flag. The variable could only render the flag in quotes, at best, which does not work with cobra.

My solution to this is to set the env either in the systemd drop-in ; and have the visor detect this env directly rather than requiring it's flag.

The default value of the -m flag for skywire-visor is changed to true if the AUTOPEER env equals the string "1"

Did you run make format && make check?
yes

Changes:

• activate autopeering on AUTOPEER=1 if SKYBIAN=true

How to test this PR:

AUTOPEER=1 SKYBIAN=true skywire-visor --all