[scripts] Create a script for configuring user credentials

Summary: issue: ENG-6615

Test Plan:
I added node $PRJ_ROOT/scripts/set-admin-data.js to dev-shell.nix:

Reviewers: tomek, michal, ashoat

Reviewed By: tomek, ashoat

Subscribers: ashoat

Differential Revision: https://phab.comm.dev/D11075