add script to update/maintain channel lists

Script downloads channels lists, sorts, and separates into NDS and
EPICS lists based on sample rate.
3 jobs for update-script in 11 minutes and 45 seconds (queued for 2 seconds)
latest
Status Job ID Name Coverage
  Build And Test
passed #247690
ligo-channel-completion:buster

00:01:22

passed #247692
ligo-channel-completion:jessie

00:11:45

passed #247691
ligo-channel-completion:stretch

00:01:11