Assigns a new string to a stringfish vector or any other character vector
Details
A function to assign a new element to an existing character vector. If the the vector is a stringfish vector, it does so without materialization.
Examples
if(getRversion() >= "3.5.0") {
x <- sf_vector(10)
sf_assign(x, 1, "hello world")
sf_assign(x, 2, "another string")
}