services: convert to VERB_COMMAND and add --introspect-cli

This converts systemd-homed, -hostnamed, -importd, -localed, -logind,
-machined, -networkd, -portebled, -resolved, -sysupdated, -timedated,
and -timesyncd.

The service name and description move from service_parse_argv() arguments
into a COMMAND() description that each daemon now defines. The
service_parse_argv() macro captures the calling binary's verb section,
where that COMMAND is found, while the options are still defined and
parsed in libshared, in the new "service" option namespace that each
COMMAND references. (The named namespace makes sure that options defined
by other translation units in libshared can never leak into the
services' parsers.)

The supported features are declared via option group filtering: each
COMMAND lists "Options" plus "Bus introspection" and/or "Runtime scope".
Unsupported options are now rejected by the parser as unknown options
(and are not shown in --help), replacing the runtime "This service does
not support …" errors.

The help output changes slightly: the "Bus introspection" and "Runtime
scope" option groups now get their own headings, and some descriptions
were reworded to the imperative form used elsewhere.

test/units/TEST-74-AUX-UTILS.introspect-cli.sh

@@ -66,25 +66,32 @@ INTROSPECTABLE=(
     systemd-firstboot
     systemd-growfs
     systemd-hibernate-resume
+    systemd-homed
+    systemd-hostnamed
     systemd-hwdb
     systemd-id128
     systemd-imds
     systemd-imdsd
     systemd-import
     systemd-import-fs
+    systemd-importd
     systemd-inhibit
     systemd-integritysetup
     systemd-journal-gatewayd
     systemd-journal-remote
     systemd-journal-upload
     systemd-keyutil
+    systemd-localed
+    systemd-logind
     systemd-machine-id-setup
+    systemd-machined
     systemd-measure
     systemd-modules-load
     systemd-mount
     systemd-mstack
     systemd-mute-console
     systemd-network-generator
+    systemd-networkd
     systemd-networkd-wait-online
     systemd-notify
     systemd-nspawn
@@ -92,6 +99,7 @@ INTROSPECTABLE=(
     systemd-path
     systemd-pcrextend
     systemd-pcrlock
+    systemd-portabled
     systemd-pty-forward
     systemd-pull
     systemd-random-seed
@@ -102,6 +110,7 @@ INTROSPECTABLE=(
     systemd-report-files
     systemd-report-sign-plain
     systemd-report-sign-tsm
+    systemd-resolved
     systemd-run
     systemd-sbsign
     systemd-sleep
@@ -116,7 +125,10 @@ INTROSPECTABLE=(
     systemd-sysext
     systemd-sysinstall
     systemd-sysupdate
+    systemd-sysupdated
     systemd-sysusers
+    systemd-timedated
+    systemd-timesyncd
     systemd-tmpfiles
     systemd-tpm2-clear
     systemd-tpm2-setup
@@ -181,6 +193,14 @@ systemd-clonesetup --introspect-cli | jq -e \
 systemd-dissect --introspect-cli | jq -e \
     '[.commands[].names[0]] | sort == ["mount.ddi", "systemd-dissect"]'
 
+# systemd-hostnamed does not support --system/--user: options from groups not listed by the
+# command must be rejected as unknown and hidden from the introspection (option group filtering)
+if command -v systemd-hostnamed >/dev/null; then
+    (! systemd-hostnamed --system 2>&1) | grep "unrecognized option" >/dev/null
+    systemd-hostnamed --introspect-cli | jq -e \
+        'all(.commands[]; all(.options[]; .names[-1] != "--system"))'
+fi
+
 systemd-id128 --introspect-cli | jq -e \
     '.commands[0].verbs | map(.names[0]) | contains(["new", "machine-id", "show", "help"])'