Rework dev bundle patch generation to not use GNU diff

[jpenilla]

This is generally not very high priority as most of the time dev bundles will be generated by CI and published to maven, but it would be nice to not need GNU diff for dev bundle generation, for easier local testing on macOS (for those who for some reason don't install GNU coreutils) and Windows.

Two possible alternatives are

• Using git to generate the patches (looked into briefly before and didn't have much luck, but I was probably missing something obvious)
• Using Diff4j/Diffpatch/something else to generate the patches

[rgnter]

GNU DiffUtils does not have --color option. This should be marked as bug, not an "enhancement".

[MiniDigger]

GNU DiffUtils does not have --color option. This should be marked as bug, not an "enhancement".

thats wrong https://www.gnu.org/software/diffutils/manual/diffutils.html#index-color_002c-distinguishing-different-context

[rgnter]

It's not available in prebuilt version 2.8.

[NotMyFault]

In 10 days, 2.8 celebrates 20th anniversary. --color was originally introduced in 3.4, but you should update to the newest release from a few months ago; 3.8.
However, I'm currently on 3.7 and it works out of the box as well.

[rgnter]

It's not available standalone, after installing pacman I finally managed to get it.