feat: add --new-file arg to diff command

[deroke]

When i compare two versions of a package new/deleted files aren't diffed correctly (in my opinion).

Example:

diff --recursive --unified --exclude test --exclude Makefile <package@1> <package@2>

# new files
Only in <package@1>: some-file-1.txt

# deleted files
Only in <package@2>: some-file-2.txt

After this PR:

diff --recursive --unified --new-file --exclude test --exclude Makefile <package@1> <package@2>

# new files
--- <package@1>/some-file-1.txt	1970-01-01 01:00:00.000000000 +0100
+++ <package@2>/some-file-1.txt	2021-09-09 11:11:11.000000000 +0200
@@ -0,0 +1,9 @@
+this is a test

# deleted files
--- <package@1>/some-file-2.txt	1970-01-01 01:00:00.000000000 +0100
+++ <package@2>/some-file-2.txt	2021-09-09 11:11:11.000000000 +0200
@@ -1,9 +0,0 @@
-this is another test

https://man7.org/linux/man-pages/man1/diff.1.html

[juliangruber]

Perfect, makes a lot of sense, that's why I love open source. Thank you so much!

https://github.com/juliangruber/npm-diff/releases/tag/v2.0.1