[Rules] Allow TargetGroup as Rule Condition

[solverat]

Q	A
Bug report?	no
Feature request?	yes
BC Break report?	no
RFC?	no

It would be nice to determinate some price rules based on assigned target groups (Defined in "Personalization / Targeting")

[dpfaffenbauer]

Since Targeting is only frontend-wise available: we also have to store the target-group into the cart/order/quote in order to get it for rules...