This modification will allow users that use specific distributions (example: Ubuntu 18.04) to use the OpenVPN scripts without getting any strange behavior on interface detection.
This commits will be reviewed in the next commit, to align coding style with the entire project.
The merge request from @triffid included the following commits:
* connect_to_wireguard_with_token: Check if "jq" and "curl" are available, allow script to issue multiple errors in a single invocation
* connect_to_wireguard_with_token: ensure /etc/wireguard exists
* connect_to_wireguard_with_token: only complain about ipv6 if it's not already disabled
* get_region_and_token: allow specifying maximum latency via environment variable, retain 50ms default
* connect_to_wireguard_with_token: pack tool checks within a function
* get_region_and_token: rename maximum_allowed_latency -> MAX_LATENCY
