chore(repo): add git attributes configuration (#29584)

Issue number: N/A

---------

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## What is the current behavior?
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## What is the new behavior?
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add a .gitattributes configuration file to the repo. this will allow
users of unix and windows machines to be able to commit to the repo
without worrying about line endings.

previously, running the `lint` npm task in the core directory would
cause the line endings to change locally. with this change, line endings
should not change

## Does this introduce a breaking change?

- [ ] Yes
- [x] No

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## Other information

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Author: rwaskiewicz

core/.gitattributes

@@ -0,0 +1 @@
+* text=auto eol=lf