GtkTemplate : Allow resources from pre compiled data
currently with Vala, XML resource file is required : https://gitlab.gnome.org/GNOME/vala/blob/master/codegen/valagtkmodule.vala#L138
If this file is missing, build fails. Allowing import of already pre compiled resources (with glib-compile-resources or other app) could be a good idea.
example : With meson system and his GNOME module, you can compile resource and use the result as source object inside your meson main project