Would a default control function be worthwhile?

I wonder if this should call a `default_control()` function. This may be a little more tractable/transparent?

https://github.com/epiverse-trace/finalsize/blob/e059839623bd39504873eae5de6916a28fa643e8/R/final_size.R#L128-L134

It could become something like

```r
final_size <- function(r0 = 2.0,
contact_matrix,
demography_vector,
p_susceptibility,
susceptibility,
solver = c("iterative", "newton"),
control = default_controls(solver)) {
```