cmd/app: multiple template uppers

Having multiple environments is useful, and this was trivial to implement.

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

cmd/app/app_test.go

@@ -20,7 +20,7 @@ func TestParse(t *testing.T) {
 		want *hst.Config
 		err  error
 	}{
-		{"com.discordapp.Discord", `8
+		{"com.discordapp.Discord", `nonfree:8
 exec Discord --ozone-platform-hint=wayland
 
 gpu
@@ -74,9 +74,9 @@ talk com.canonical.Unity
 					{FilesystemConfig: &hst.FSOverlay{
 						Target: fhs.AbsRoot,
 						Lower: []*check.Absolute{
-							base.Append("template", "initial"),
+							base.Append("initial"),
 						},
-						Upper: base.Append("template", "upper"),
+						Upper: base.Append("template", "nonfree", "upper"),
 					}},
 					{FilesystemConfig: &hst.FSBind{
 						Target: hst.AbsPrivateTmp.Append("home"),