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
