Fixes #157

This is an initial attempt at enabling the git warning for a missing newline character at the end of the file.

There are 3 different scenarios where this can occur, if the old changes contained the missing character, the new changes are missing it, or if both old and new are missing the character.

While the line-by-line renderer was able to work with the warning simply classified as a context line, this was not the case for side-by-side.

In side-by-side rendering, it would insert the message in both sides even if it was only applicable to one or the other. So a little more legwork was required to capture that metadata in order to appropriately insert it and a corresponding empty line for the other side.

In issue #157, I found a linked PR with some files missing newline characters I used as guidance (azaria-dedmon/covid-19#37)

Here is the demo app rendering them in both
Line-by-Line

Side-by-Side