Swap in new JSON distributions in server code

[dehann]

Use IIF v0.27 distribution packing types instead of legacy duplicates:

https://github.com/JuliaRobotics/Caesar.jl/blob/master/src/zmq/models/distributions.jl

New IIF v0.27 ones here:

https://github.com/JuliaRobotics/IncrementalInference.jl/tree/master/src/Serialization/entities