Enhancement: support for glmtoolbox glmgee objects

[mlotinga]

Super package. It would be great to see support extended to the glmtoolbox glmgee S3 object models for Generalized Estimating Equations (GEE) solution to GLMs.

https://cran.r-project.org/web/packages/glmtoolbox/index.html
https://journal.r-project.org/articles/RJ-2023-056