meson.build: add option to install the legacy xorg symlinks
console-setup still relies on the xorg ruleset [1] and there may be other tools out there. Let's provide an equivalent option to our autotools build to install the xorg symlinks.
Note that unlike the autotools approach, only the "xorg" symlinks are provided, not the well and truly legacy "xfree86" ones.
[1] https://salsa.debian.org/installer-team/console-setup/-/merge_requests/7/