`read_zarr_array` sorts permuted full indices from `index`

[Artur-man]

I came across with a strange behaviour of read_zarr_array.

> mat <- array(1:25, dim = c(5,5))
> mat
     [,1] [,2] [,3] [,4] [,5]
[1,]    1    6   11   16   21
[2,]    2    7   12   17   22
[3,]    3    8   13   18   23
[4,]    4    9   14   19   24
[5,]    5   10   15   20   25
> mat_zarr <- as(mat, "ZarrArray")
> set.seed(1)
> index <- list(sample(1:5,5), NULL)
> index
[[1]]
[1] 1 4 3 5 2

[[2]]
NULL

> Rarr::read_zarr_array(mat_zarr@seed@zarr_path, index)
     [,1] [,2] [,3] [,4] [,5]
[1,]    1    6   11   16   21
[2,]    2    7   12   17   22
[3,]    3    8   13   18   23
[4,]    4    9   14   19   24
[5,]    5   10   15   20   25

This does not happen if indices are a subset, but not a permutation of the full index set.

> mat <- array(1:25, dim = c(5,5))
> mat
     [,1] [,2] [,3] [,4] [,5]
[1,]    1    6   11   16   21
[2,]    2    7   12   17   22
[3,]    3    8   13   18   23
[4,]    4    9   14   19   24
[5,]    5   10   15   20   25
> mat_zarr <- as(mat, "ZarrArray")
> set.seed(1)
> index <- list(sample(1:5,3), NULL)
> index
[[1]]
[1] 1 4 3

[[2]]
NULL

> Rarr::read_zarr_array(mat_zarr@seed@zarr_path, index)
     [,1] [,2] [,3] [,4] [,5]
[1,]    1    6   11   16   21
[2,]    4    9   14   19   24
[3,]    3    8   13   18   23

[Bisaloo]

Reopening because we still need to add a test case for this.