Consolidate load strategies within receiver

This pull request adds load strategies originally intended for `casa-relay` and `casa-local` (the latter not implemented yet) because otherwise they'll be implemented multiple times. The `LoadFromAdjInStore` strategy is actually powerful enough that, at a later date, we might want to break it out into its own feature, since there will be an `Local -> AdjOut` operation as well that could also leverage this one.