sorted option not enforced when sort violations bridge NA

[bifouba]

This fails as expected:
checkmate::check_integerish(c(2, 1), sorted = TRUE)

The mere presence of NAs is not an issue, as these continue to fail as expected:
checkmate::check_integerish(c(2, 1, NA), sorted = TRUE)
checkmate::check_integerish(c(NA, 2, 1), sorted = TRUE)

BUT if the sort order violation is interrupted by NA, it remains unnoticed.
The following incorrectly returns TRUE:
checkmate::check_integerish(c(2, NA, 1), sorted = TRUE)

[tdeenes]

@mllg This is a bug in is_sorted_double. I will prepare a PR in a minute.

[tdeenes]

fixed in PR