Soft deprecation warnings of `vctrs_vec_compat()` don't bubble up

[DavisVaughan]

i.e. should see a warning here

purrr::map(pairlist(1, 2), identity)
#> [[1]]
#> [1] 1
#> 
#> [[2]]
#> [1] 2

I think we need to pass the user_env down to vctrs_vec_compat(), which may be annoying

grep for any usage of deprecate_soft() to make sure we get them all

[hadley]

Two other functions need similar tweaks: deprec_rerun() and where_at().