vctrs objects loose names when apply is used on them

[thomasp85]

It appears vctrs objects will throw away their names when mapped over, in contrast to how names generally behaves with mapping (the names is transferred to the result)

names(lapply(vctrs::new_vctr(list(a = 1, b = 2)), identity))
#> NULL
names(lapply(list(a = 1, b = 2), identity))
#> [1] "a" "b"

This is due to as.list() throwing away the names

[DavisVaughan]

I think this is actually a duplicate of #1416