Ensure to have filesystem tools installed

When installing to an XFS root partition, update-initramfs complains:

| update-initramfs: Generating /boot/initrd.img-5.10.0-19-amd64
| W: /sbin/fsck.xfs doesn't exist, can't install to initramfs

Let's make sure to have the according filesystem package available.

FTR, no need for handling ext* + e2fsprogs, as this is available anyways
due to `Priority: required`.

Also, the "--filesystem jfs" isn't supported by default (as mkfs.jfs
expects user input unless invoked with -q, something we might wanna
automate in the future?), but someone can prepare it manually and
install it to the mounted file system, so let's also handle this.

Thanks: Chris Hofstaedtler for the bug report
Closes: https://github.com/grml/grml-debootstrap/issues/200