systemd: add libblkid and libfdisk PACKAGECONFIG options

systemd: add libblkid and libfdisk PACKAGECONFIG options

Introduce new PACKAGECONFIG options in systemd for both libblkid and
libfdisk [1][2].

Set blkid as enabled by default because the bootctl command depends
on it to be built. For example, images like core-image-sato-sdk rely on
bootctl and have specific tests for it.

Previously this worked implicitly because the upstream Meson option
defaulted to auto, which enabled the dependency if libblkid was present.
Now, without explicitly enabling it via PACKAGECONFIG, the feature would
be disabled, which triggers testimage errors.

[1] https://github.com/systemd/systemd/blob/main/README#L219
[2] https://github.com/systemd/systemd/blob/main/README#L228

Signed-off-by: Hiago De Franco <hiago.franco@toradex.com>
Signed-off-by: Mathieu Dubois-Briand <mathieu.dubois-briand@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>