Backend configuration prevent testing

[thewilkybarkid]

Background configuration is read by a single module and is then directly used by various places in the codebase, such as

prereview/src/backend/middleware/auth.js

Lines 41 to 56 in d542241

	roles.isMemberOf = async (group, id) => {
	log.debug(`Checking if ${id} is a member of ${group}.`);
	if (
	config.adminUsers &&
	group === 'admins' &&
	isString(id) &&
	orcidUtils.isValid(id)
	) {
	return (
	config.adminUsers.includes(id) ||
	(await groups.isMemberOf('admins', id))
	);
	} else {
	return groups.isMemberOf(group, id);
	}
	};

This module contains all sorts of things not used (e.g. command-line options), but the main problem is that it reads from the environment/.env file and doesn't allow it to be changed programmatically, making testing impossible (refs #388, #400 (comment)).

Configuration needs to be changed so that it's passed in from the outside, allow tests to set it as needed.