systemd-analyze: add --root option for 'verify' verb and allow path parsing

-------------------------------------------------------------------------------
Example Run:

foobar.service created below is a service unit file that has a non-existing key-value
pairing (foo = bar) and is thus, syntactically invalid.

maanya-goenka@debian:~/systemd (img-support)$ cat <<EOF>img/usr/lib/systemd/system/foobar.service
> [Unit]
> foo = bar
>
> [Service]
> ExecStart = /opt/script0.sh
> EOF

The failure to create foobar.service because of the recursive dependency searching and verification has been addressed
in a different PR: systemd-analyze: add option to return an error value when unit verification fails #20233

maanya-goenka@debian:~/systemd (img-support)$ sudo build/systemd-analyze verify --root=img/ foobar.service
/home/maanya-goenka/systemd/img/usr/lib/systemd/system/foobar.service:2: Unknown key name 'foo' in section 'Unit', ignoring.
foobar.service: Failed to create foobar.service/start: Unit sysinit.target not found.

1 files changed, 1 insertions, 1 deletions

diff --git a/src/test/test-bpf-foreign-programs.c b/src/test/test-bpf-foreign-programs.c
index a6f8eb6f4a..bbf3916872 100644
--- a/src/test/test-bpf-foreign-programs.c
+++ b/src/test/test-bpf-foreign-programs.c
@@ -304,7 +304,7 @@ int main(int argc, char *argv[]) {
         assert_se(runtime_dir = setup_fake_runtime_dir());
 
         assert_se(manager_new(UNIT_FILE_USER, MANAGER_TEST_RUN_BASIC, &m) >= 0);
-        assert_se(manager_startup(m, NULL, NULL) >= 0);
+        assert_se(manager_startup(m, NULL, NULL, NULL) >= 0);
 
         assert_se(test_bpf_cgroup_programs(m,
                                 "single_prog.service", single_prog, ELEMENTSOF(single_prog)) >= 0);