feat(aptitude): update sub-commands

The following commands are listed in the manpage and were missing from
the completion file:

    build-depends
    extract-cache-subset
    help

Whereas the following commands are not listed in the manpage nor in the
documentation:

    dist-upgrade
    upgrade

Moreover, build-depends and build-deps are aliases, and bash-completion
guidelines (CONTRIBUTING.md) recommend using the longer version.

This patch updates the list and sorts it by-name.

Suggested-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Suggested-by: Koichi Murase <myoga.murase@gmail.com>

Author: inconstante

completions/aptitude

@@ -94,11 +94,11 @@ _comp_cmd_aptitude()
         _comp_compgen -- -W '"${COMPREPLY[@]}"' \
             ${exclude_flags:+-X "-[$exclude_flags]"}
     else
-        _comp_compgen -- -W 'update upgrade safe-upgrade forget-new clean
-            autoclean install reinstall remove hold unhold purge markauto
-            unmarkauto why why-not dist-upgrade full-upgrade download search
-            show forbid-version changelog keep keep-all build-dep add-user-tag
-            remove-user-tag versions'
+        _comp_compgen -- -W 'add-user-tag autoclean build-depends changelog
+            clean download extract-cache-subset forbid-version forget-new
+            full-upgrade help hold install keep keep-all markauto purge
+            reinstall remove remove-user-tag safe-upgrade search show showsrc
+            source unhold unmarkauto update versions why why-not'
     fi
 
 } &&