Duplicate modules added to HOOKS in mkinitcpio.conf

After installation with architect on a system that uses LVM, I started to see these errors.

mkdir: can't create directory '/run/lvm': File exists

Failed to acquire lock on /run/lvmetad.pid. Already running?

The cause as described by gabe.rust in this forum post was multiple lvm2 entries being added to HOOKS= in /etc/mkinicpio.conf.

Example: HOOKS=(base udev autodetect modconf block lvm2 lvm2 filesystems keyboard)

The cause seems to be sed statements found here util-desktop.sh#L389-398 and here util-base.sh#L322-331. When the aforementioned code is run after util-desktop.sh#L435-437 and util-base.sh#L368-370, duplicate modules will be added.

!253 (merged) should resolve the duplicates by updating the sed statements to only insert if the module being added isn't already present in the line.