app: integrate container autoroot

Doing this instead of mounting directly on / because it's impossible to ensure a parent is available for every path hakurei wants to mount to. This situation is similar to autoetc hence the similar name, however a symlink mirror will not work in this case.

Signed-off-by: Ophestra <cat@gensokyo.uk>

hst/template_test.go

@@ -126,6 +126,8 @@ func TestTemplate(t *testing.T) {
 				"/run/user/150"
 			]
 		],
+		"auto_root": "/var/lib/hakurei/base/org.debian",
+		"root_flags": 2,
 		"etc": "/etc",
 		"auto_etc": true,
 		"cover": [