analyze: extend the dump command to accept patterns

The new function DumpPatterns() can be used to limit (drastically) the size of
the data returned by PID1. Hence the optimization of serializing data into a
file descriptor should be less relevant than having the possibility to limit
the data when communicating with the service manager remotely.

NB: when passing patterns, the dump command omits the version of the manager as
well as the features and the timestamps.

shell-completion/bash/systemd-analyze

@@ -60,9 +60,10 @@ _systemd_analyze() {
     )
 
     local -A VERBS=(
-        [STANDALONE]='time blame plot dump unit-paths exit-status calendar timestamp timespan'
+        [STANDALONE]='time blame plot unit-paths exit-status calendar timestamp timespan'
         [CRITICAL_CHAIN]='critical-chain'
         [DOT]='dot'
+        [DUMP]='dump'
         [VERIFY]='verify'
         [SECCOMP_FILTER]='syscall-filter'
         [CAT_CONFIG]='cat-config'
@@ -125,6 +126,13 @@ _systemd_analyze() {
             comps='--help --version --system --user --global --from-pattern --to-pattern --order --require'
         fi
 
+    elif __contains_word "$verb" ${VERBS[DUMP]}; then
+        if [[ $cur = -* ]]; then
+            comps='--help --version --system --user --no-pager'
+        else
+            comps=$( __get_units_all )
+        fi
+
     elif __contains_word "$verb" ${VERBS[SECCOMP_FILTER]}; then
         if [[ $cur = -* ]]; then
             comps='--help --version --no-pager'