paymentsservice: structure logs

[naseemkullah]

Use Pino's mergingObject parameter to add context as JSON rather than in the message parameter, which is now more generic (like an event name).

Also factor out logger so it is instantiated once for the whole service and upgrade pino.

Also remove unneeded comments.

[naseemkullah]

please remove the hardcoded default port, the rest looks great.

Thanks!

done, my pleasure

[mic-max]

LGTM!