Add a TEST-87 testcase exercising "bootctl link-auto" and the equivalent
io.systemd.BootControl.LinkAuto() Varlink method: a UKI plus extras are staged
below the search directories and we assert the kernel and sidecar resources
are linked into $BOOT. Covered: plain kernel.efi + extras.d/, versioned
kernel.efi.v/ and extras .v/ resolved via vpick, directory priority
(/etc wins over /run), the no-op case when nothing is staged, and the Varlink
method including its empty reply when there is nothing to link.
Lennart Poettering
9ac1b6c124