Simplify the addition of new structs

[jd-lara]

@daniel-thom, this issue summarizes our conversation

1. automate the code auto generation in CI for users by adding a new struct
2. add a specific workflow such that the users only needs to check in the new struct blob and not modify the larger structs JSON file.
3. add template for the new structs when users want them.
4. Improve documentation.

[jd-lara]

x-ref to a similar problem: https://github.com/NREL-SIIP/PowerSystems.jl/issues/904

[daniel-thom]

@jd-lara Do you consider this fixed?