new: usr: add extra tokens to the zone file name template

Extend the `$name`, `$view` and `$type` tokens (expanding into the zone
name, zone's view name and type); the new following tokens are now also
accepted:

- `$name` or `%s` is replaced with the zone name in lower case;
- `$type` or `%t` is replaced with the zone type -- i.e., primary,
  secondary, etc);
- `$view` or `%v` is replaced with the view name;
- `$char1` or `%1` is replaced with the first character of the zone name;
- `$char2` or `%2` is replaced with the second character of the zone name
  (or a dot if there is no second character);
- `$char3` or `%3` is replaced with the third character of the zone name (or
  a dot if there is no third character);
- `$label1` or `%z` is replaced with the toplevel domain of the zone (or a
  dot if it is the root zone);
- `$label2` or `%y` is replaced with the next label under the toplevel
  domain (or a dot if there is no next label);
- `$label3` or `%x` is replaced with the next-next label under the toplevel
  domain (or a dot if there is no next-next label).

Closes #85

Merge branch '85-file-template' into 'main'

See merge request isc-projects/bind9!10779