Introduce code that makes use of the information from
pySim.esim.saip.templates to build a complete representation of a file
by merging the template with the ProfileElement decribing the file.
This happens within the class pySim.esim.saip.File, whose instances are
created from ProfileElement + Template.
Change-Id: Ib1674920e488ade9597cb039e4e2047dcbc7864e
d16a20ccc3