Each target can specify own template. This is however not recommended for general use.
Each target should be supported by progendef, and well definied. However, as tools are
quickly changing, some targets add extra information which might not be supported, this
template expansion allows a target to temporary override default mbed tool template.

In this commit, we add RZ_A1H iar template. I experienced with never tools some breakage in
the templates, this might come handy, but repeat, please consider using the default template, and
contribute to progen or progendef which should contain fixes or support for newer targets/tools.