xbps-reconfigure: add ability to reconfigure dependencies

[classabbyamp]

adds -x/--deps and --fulldeptree, that behave similar to the xbps-query modes

fixes #464

Sample Output

$ doas bin/xbps-reconfigure/xbps-reconfigure -fx linux  
linux5.15: configuring ...
Executing post-install kernel hook: 20-dracut ...
dracut: dracut module 'cifs' depends on 'network', which can't be installed
Mode:           real
Files:          2593
Linked:         221 files
Compared:       0 xattrs
Compared:       3866 files
Saved:          17.58 MiB
Duration:       0.030899 seconds
Executing post-install kernel hook: 50-efibootmgr ...
Executing post-install kernel hook: 50-grub ...
Generating grub configuration file ...
Found background: /usr/share/void-artwork/splash.png
Found linux image: /boot/vmlinuz-5.15.34_1
Found initrd image: /boot/initramfs-5.15.34_1.img
Found linux image: /boot/vmlinuz-5.15.32_1
Found initrd image: /boot/initramfs-5.15.32_1.img
Found linux image: /boot/vmlinuz-5.15.30_1
Found initrd image: /boot/initramfs-5.15.30_1.img
Warning: os-prober will be executed to detect other bootable partitions.
Its output will be used to detect bootable binaries on them and create new boot entries.
Found Windows Boot Manager on /dev/nvme0n1p1@/EFI/Microsoft/Boot/bootmgfw.efi
Adding boot menu entry for UEFI Firmware Settings ...
done
linux5.15: configured successfully.
linux-base: configuring ...
linux-base: configured successfully.
linux: configuring ...
linux: configured successfully.

[classabbyamp]

This implementation is a bit naïve and will reconfigure something multiple times if it appears in the dep tree of multiple packages, argv multiple times (this happens in the old implementation too), or both. Should packages be deduplicated? I'm not sure of a good way to do this in C, if that's wanted. Suggestions?