Transports for `WeightedMeasure`

Currently we have
```julia
transport_origin(ν::WeightedMeasure) = ν.base
to_origin(::WeightedMeasure, y) = y
from_origin(::WeightedMeasure, x) = x
```

Should this be
```julia
transport_origin(ν::WeightedMeasure) = transport_origin(ν.base)
to_origin(v::WeightedMeasure, y) = to_origin(v.base, y)
from_origin(v::WeightedMeasure, x) = from_origin(v.base, x)
```
?

It seems strange for wrapping an arbitrary measure with a weight to cause the transport mechanism to "give up".