add ability to specify mkmf template by name instead of path

[rem1776]

Is your feature request related to a problem? Please describe.
The mkmf templates specified in the platform yaml require a full path to the template file, which is hard coded to static locations for each system. This works fine but is unnecessary now that we're including mkmf and all it's templates in this repo as a submodule.

Describe the solution you'd like
Instead of the mkTemplate key in the platform yaml taking a file path, it could just take the file name of the template. The code should be able to append the rest of the path and use the template file in this repo's submodule instead.

Describe alternatives you've considered
Keep as is