Returns the possible model classes that `gglm` works with.

## Note

Note that these are not always the exact name of the class that that can be used. This is due to how some methods are written in the packages `gglm` imports. For example, the model class "merMod" refers to a variety of model outputs from `lme4`, even when the outputted class is not called "merMod".

## Examples

```
list_model_classes()
#> [1] "mlogit" "rq" "logitmfx" "Mclust"
#> [5] "betamfx" "poLCA" "nls" "factanal"
#> [9] "poissonmfx" "htest" "default" "lmrob"
#> [13] "brmsfit" "prcomp" "smooth.spline" "polr"
#> [17] "glmRob" "mfx" "stl" "felm"
#> [21] "glmmTMB" "glmmadmb" "survreg" "drc"
#> [25] "fixest" "clm" "lme" "pam"
#> [29] "lm" "glmrob" "decomposed.ts" "rqs"
#> [33] "gam" "loess" "probitmfx" "negbinmfx"
#> [37] "ranef.mer" "kmeans" "merMod" "nlrq"
#> [41] "rlm" "margins" "rma" "ivreg"
#> [45] "mjoint" "sarlm" "data.frame" "speedglm"
#> [49] "plm" "coxph" "glm" "lmRob"
#> [53] "betareg" "NULL" "gamm4" "Sarlm"
#> [57] "speedlm" "gls"
```