change from individual factory env-* files in repo to local only env.factory

[vEDW]

This issue aims at removing factory specific information (env-*) from repo and use gitignored local file instead (env.factory).

There should be scripts to assist :

• in creating such local file based on existing one (migration script)
• in validating the local file has all the necessary entries (validation script)
• in creating a new one from scratch for new factories.

identified existing files to modify :

• ./env
• ./compute/modify_portgroup.ps1
• ./compute/fallback_promiscuous.ps1

if other files need to be modified, i'll add them below as comments.