[Distributed] IRGen: Support loading both concrete and generic argument values
[Distributed] IRGen: Support loading both concrete and generic argument values

To load generic argument value, we need to retrieve argument type
from the argument types buffer, based on that load value size and
alignment, and only then fetch actual value from the argument buffer
as `swift.opaque *`.

JGiola/swift,ahoppen/swift,benlangmuir/swift,roambotics/swift,gregomni/swift,apple/swift,rudkx/swift,apple/swift,roambotics/swift,ahoppen/swift,roambotics/swift,gregomni/swift,apple/swift,apple/swift,JGiola/swift,rudkx/swift,atrick/swift,JGiola/swift,glessard/swift,glessard/swift,apple/swift,atrick/swift,glessard/swift,gregomni/swift,glessard/swift,benlangmuir/swift,rudkx/swift,ahoppen/swift,atrick/swift,JGiola/swift,gregomni/swift,atrick/swift,benlangmuir/swift,ahoppen/swift,glessard/swift,rudkx/swift,JGiola/swift,gregomni/swift,roambotics/swift,atrick/swift,roambotics/swift,gregomni/swift,ahoppen/swift,roambotics/swift,benlangmuir/swift,atrick/swift,JGiola/swift,rudkx/swift,rudkx/swift,glessard/swift,ahoppen/swift,benlangmuir/swift,apple/swift,benlangmuir/swift