Materialize results in collect()

[krlmlr]

for duckplyr.

[DavisVaughan]

Do you think we can delay this one for now and keep this behavior in the collect.duckplyr_df() method that you have here?
https://github.com/duckdblabs/duckplyr/blob/main/R/collect.R

With the goal of eventually moving it to dplyr in the future if we can't come up with any better solution

[krlmlr]

Sure. This is just what I think this will need to look like long-term, we don't need to act now.