Bump faer to latest 0.18.x release (#12184)

This commit bumps the faer version used to the latest release 0.18.x.
There were some changes to the package structure in 0.18 which reduced
the number of crates used to build faer as it's now a flatter project.
However, the converter to ndarray is now in a seperate faer-ext crate
which is added to the dependencies list.