wip: simplify and automate forwarding of env vars [server -> kernel] and [gateway -> kernel]#1000

Draft

telamonian wants to merge 1 commit intojupyter-server:mainfrom telamonian:automate-kernel-env-forward

Commits on Aug 22, 2021

wip jupyter-server#957 : refactored ENV_WHITELIST -> ENV_FORWARD; automatically determine ENV_FORWARD from kernel env stanza
telamonian
committed