Create 'gen-test-report' top-level make target

[danpape]

Add new make target so that executing 'make gen-test-report' will run the implementation-report app with all paths/filenames specified.

For instance, just as we can do:

mkdir build
cd build
cmake ..
make
make test

it would be nice to also be able to say

make gen-test-report

without having to do anything more complicated.

[hawkmauk]

I had been thinking about this and wondered if the implementation report should be separated out into it's own repo as gtest2tutle or similar? If we did that then we could call it in when running make gen-test-report.
We would then just need to keep and maintain a copy of the configuration file in the repository.