Introduce user settings for ArcGIS product and license level

Ok, these 2 articles explain nicely how FME chooses from the available ArcGIS products on the system and how to "force" which license level is used:

• https://knowledge.safe.com/questions/36948/can-i-specify-whether-fme-desktop-uses-my-arcgis-d.html
• https://knowledge.safe.com/articles/31613/setting-different-license-levels-for-arcgis-and-fm.html

My proposal is to introduce FME specific environment variables (or FME options Settings) to allow the user exactly what to use at FME runtime, e.g.:

FME_ARCGIS_PRODUCT_USE=Engine|Server|Desktop
FME_ARCGIS_LEVEL_USE=Basic|Standard|Advanced

This should override the internal FME logic and of course fail, if the user chooses a product which is not installed, licensed or if the combination violates either Esri or Safe usage agreements.