udevadm: introduce new 'verify' command

We seem to have no tool to verify udev rule files.  There is a simple
udev rules syntax checker in the tree, test/rule-syntax-check.py, but
it is too simple to detect less trivial issues not detected by udev,
e.g. redundant comparisons (#26593) or labels without references.

Such a tool would be beneficial not only for maintaining udev rules
distributed along with udev, but also and even more so for maintaining
third party udev rules that are more likely to have issues with syntax
and semantic correctness.

Implement a udev rules syntax and semantics checker in the form of
'udevadm verify [OPTIONS] FILE...' command that is based on
udev_rules_parse_file() interface and would apply further checks
on top of it in subsequent commits.

Resolves: #26606

shell-completion/bash/udevadm

@@ -64,11 +64,12 @@ _udevadm() {
         [MONITOR_ARG]='-s --subsystem-match -t --tag-match'
         [TEST]='-a --action -N --resolve-names'
         [TEST_BUILTIN]='-a --action'
+        [VERIFY]='-N --resolve-names'
         [WAIT]='-t --timeout --initialized=no --removed --settle'
         [LOCK]='-t --timeout -d --device -b --backing -p --print'
     )
 
-    local verbs=(info trigger settle control monitor test-builtin test wait lock)
+    local verbs=(info trigger settle control monitor test-builtin test verify wait lock)
     local builtins=(blkid btrfs hwdb input_id keyboard kmod net_id net_setup_link path_id usb_id uaccess)
 
     for ((i=0; i < COMP_CWORD; i++)); do
@@ -247,6 +248,27 @@ _udevadm() {
             fi
             ;;
 
+        'verify')
+            if __contains_word "$prev" ${OPTS[VERIFY]}; then
+                case $prev in
+                    -N|--resolve-names)
+                        comps='early never'
+                        ;;
+                    *)
+                        comps=''
+                        ;;
+                esac
+                COMPREPLY=( $(compgen -W '$comps' -- "$cur") )
+                return 0
+            fi
+
+            if [[ $cur = -* ]]; then
+                comps="${OPTS[COMMON]} ${OPTS[VERIFY]}"
+            else
+                comps=$( compgen -A file -- "$cur" )
+            fi
+            ;;
+
         'wait')
             if __contains_word "$prev" ${OPTS[WAIT]}; then
                 case $prev in