This is unsafe and we debated re-adding it to the v2/2.0 codebase,
however it is a common-enough feature that we will simply mark it
as deprecated for now and remove it at some point in the future.
Fixes#11718
- now obeys global undefined var setting and allows override (mostly for with_ )
- moved environment instanciation to init instead of each template call
- removed hardcoded template token matching and now use actually configured tokens, now it won't break if someone changes default configs in ansible.cfg
- made reenetrant template calls now pass the same data it got, dictionary and lists were loosing existing and new params
- moved fail_on_undeinfed parameter to template call, as it should only realky be set to false on specific templates and not globally
- added overrides, which will allow template to implement jinja2 header override features
- added filter list to overrides to disallow possibly insecure ones, TODO: check if this is still needed as facts should not be templated anymore
- TODO: actually implement jinja2 header overrides
