Add vetiver support for glm()

[juliasilge]

library(vetiver)
cars_glm <- glm(mpg ~ ., data = mtcars)
v <- vetiver_model(cars_glm, "cars_gaussian")
v
#> 
#> ── cars_gaussian ─ <butchered_glm> model for deployment 
#> A generalized linear model (gaussian family, identity link) using 10 features


library(pins)
model_board <- board_temp()
vetiver_pin_write(model_board, v)
#> Creating new version '20220209T001336Z-2ad1f'
#> Writing to pin 'cars_gaussian'
#> 
#> Create a Model Card for your published model
#> • Model Cards provide a framework for transparent, responsible reporting
#> • Use the vetiver `.Rmd` template as a place to start

library(plumber)
pr() %>% vetiver_pr_predict(v)
#> # Plumber router with 2 endpoints, 4 filters, and 0 sub-routers.
#> # Use `pr_run()` on this object to start the API.
#> ├──[queryString]
#> ├──[body]
#> ├──[cookieParser]
#> ├──[sharedSecret]
#> ├──/ping (GET)
#> └──/predict (POST)

^{Created on 2022-02-08 by the reprex package (v2.0.1)}

Right now one of the tests has ignore_function_env = TRUE, ignore_formula_env = TRUE because the butcher method isn't great. I have opened tidymodels/butcher#211 to fix that.