shell completion: add kernel-identify/inspect verbs for bootctl

Follow-up for a05255981b
Follow-up for 3e0a3a0259

(cherry picked from commit 6a6d4c3f3c)
(cherry picked from commit 769997ee17)

shell-completion/bash/bootctl

@@ -71,6 +71,7 @@ _bootctl() {
         [STANDALONE]='help status install update remove is-installed random-seed systemd-efi-options list set-timeout set-timeout-oneshot cleanup'
         [BOOTENTRY]='set-default set-oneshot unlink'
         [BOOLEAN]='reboot-to-firmware'
+        [FILE]='kernel-identify kernel-inspect'
     )
 
     for ((i=0; i < COMP_CWORD; i++)); do
@@ -101,6 +102,9 @@ _bootctl() {
         fi
     elif __contains_word "$verb" ${VERBS[BOOLEAN]}; then
         comps="yes no"
+    elif __contains_word "$verb" ${VERBS[FILE]}; then
+        comps=$( compgen -A file -- "$cur" )
+        compopt -o filenames
     fi
 
     COMPREPLY=( $(compgen -W '$comps' -- "$cur") )