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

The verbs declare their subcommand option namespaces, so the
introspection data describes the options of every subcommand, nested in
the verb objects.

The bare version number output (a dracut compatibility requirement) is
preserved for --version/-V and the "version" verb.

The "lock" verb's argument specification is simplified to "COMMAND" --
other verbs do not mention their options in the argspec either, and the
subcommand help states where the options may go.

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

@@ -143,6 +143,7 @@ INTROSPECTABLE=(
     systemd-vmspawn
     systemd-vpick
     timedatectl
+    udevadm
     updatectl
     userdbctl
     v4l_id
@@ -208,6 +209,11 @@ fi
 systemd-id128 --introspect-cli | jq -e \
     '.commands[0].verbs | map(.names[0]) | contains(["new", "machine-id", "show", "help"])'
 
+# udevadm's verbs carry their own options, reported recursively
+udevadm --introspect-cli | jq -e \
+    '.commands[] | select(.names[0] == "udevadm") | .verbs[] | select(.names[0] == "info") |
+        [.options[].names[-1]] | contains(["--query", "--json", "--no-pager"])'
+
 # systemd is optionally a multicall binary that also provides systemd-executor
 if [[ "$(readlink "$(command -v systemd-executor)" 2>/dev/null)" == systemd ]]; then
     systemd --introspect-cli | jq -e \