Missing struct DataLogEntries

[auscompgeek]

We have NetworkTables entries that spit out structs, but not DataLog entries like C++/Java has.

https://robotpy.readthedocs.io/projects/robotpy/en/stable/wpiutil.log.html

https://github.wpilib.org/allwpilib/docs/release/java/edu/wpi/first/util/datalog/package-summary.html