Extract packages' settings dir to common/settings in image

That's a somewhat crude initial approach to installing the default
settings of packages when building the image.

build/jam/ImageRules

@@ -883,6 +883,9 @@ rule AddBootModuleSymlinksToHaikuImage targets
 
 rule AddPackageFilesToHaikuImage location : packages
 {
+	HAIKU_PACKAGES_IN_IMAGE on $(HAIKU_IMAGE_CONTAINER_NAME)
+		= [ on $(HAIKU_IMAGE_CONTAINER_NAME) return $(HAIKU_PACKAGES_IN_IMAGE) ]
+			$(packages) ;
 	AddFilesToHaikuImage $(location) packages : $(packages) ;
 }