Should we move investment cost from asset_commission to asset_milestone?

[abelsiqueira]

Tagging @gnawin and @datejada

[gnawin]

The reason that it is now in asset_commission is that we know it depends on commission years.

However, we only use it for milestone years, so it's now more natural to me to move that. I think the data in TEM should be prepared in a way that it is only relevant to TEM and everything before that should be in the "user data".