Implement promote_to_multi when converting WKB to sfc

[paleolimbot]

Apologies for taking so long to circle back here, but this is one approach to ensuring that R CMD check passes when R_SF_ST_READ_USE_STREAM=true. It also has the nice side-effect that use_stream = TRUE no longer uses the wk package to construct sfc objects and that all users of st_as_sfc(<WKB>) can now use promote_to_multi = TRUE to get the same read-ogr-like behaviour.

Closes #2296.

Example:

library(sf)

vec <- st_sfc(
    st_point(c(0, 1)),
    st_point(),
    st_point(c(2, 3)),
    st_multipoint(matrix(c(4, 5), ncol = 2))
)

wkb_vec <- st_as_binary(vec)

st_as_sfc(wkb_vec, promote_to_multi = FALSE)
st_as_sfc(wkb_vec, promote_to_multi = TRUE)

I do still see:

Failure (test-tm.R:20:3): st_read and write handle date and time
x[["tm"]] not equal to x2[["tm"]].
Attributes: < Component “tzone”: 1 string mismatch >

Failure (test-tm.R:40:3): st_read and write handle date and time
x[["tm"]] not equal to x2[["tm"]].
Attributes: < Component “tzone”: 1 string mismatch >

...when running testthat::test_local() with R_SF_ST_READ_USE_STREAM=true. I think this happens because of how nanoarrow converts timestamps without an explicit timezone to R objects: nanoarrow assigns UTC as opposed to setting tzone = "" or omitting it. I copied this behaviour from readr because it is more reproducible between systems, but I'm not sure it's any more or less correct.