Normalize all the line endings

[nimrof]

Fixing the mixed line ending in the .cs files.

Did the following:

• Added the .gitattributes file
• git rm -rf --cached .
• git reset --hard HEAD
• commit the changes

ref:
https://docs.github.com/en/get-started/getting-started-with-git/configuring-git-to-handle-line-endings

[trojanobelix]

Nice! That was always very annoying.

[CANopenNode]

Yes, nice.
Please, don't wait for me with merging. You two both are able to merge into main or whatever. @trojanobelix, if this or some other PR is OK for you, just confirm and merge it.