apt-shell: show up "list" command by completion (#5953)

And also added it to help output.

apt-0.5.15lorg2-alt-apt-shell_list_completion.patch

@@ -0,0 +1,16 @@
+
+https://bugzilla.altlinux.org/show_bug.cgi?id=5953
+
+diff --git a/apt/cmdline/apt-shell.cc b/apt/cmdline/apt-shell.cc
+index 6d1f767..76bd840 100644
+--- a/apt/cmdline/apt-shell.cc
++++ b/apt/cmdline/apt-shell.cc
+@@ -4087,7 +4099,7 @@ char *ReadLineCompCommands(const char *Text, int State)
+ 	 "keep", "dist-upgrade", "dselect-upgrade", "build-dep", "clean",
+ 	 "autoclean", "check", "help", "commit", "exit", "quit", "status",
+ 	 "showpkg", "unmet", "search", "depends", "whatdepends", "rdepends",
+-	 "show", "script", 0};
++	 "show", "script", "list", "ls", 0};
+    static int Last;
+    static int Len;
+    if (State == 0) {

apt.spec

@@ -68,6 +68,7 @@ Patch56: apt-0.5.15lorg2-lorg-pkgcachegen-selfprov.patch
 Patch57: apt-0.5.15lorg2-alt-genpkglist-no-fileflags.patch
 Patch58: apt-0.5.15lorg2-lorg-cache-limit.patch
 Patch59: apt-0.5.15lorg2-alt-gcc4.3.patch
+Patch60: apt-0.5.15lorg2-alt-apt-shell_list_completion.patch
 
 # Normally not applied, but useful.
 Patch101: apt-0.5.4cnc9-alt-getsrc-debug.patch
@@ -267,6 +268,7 @@ This package contains method 'rsync' for APT.
 %patch57 -p1
 %patch58 -p1
 %patch59 -p1
+%patch60 -p2
 
 find -type f -name \*.orig -delete