chore(repo): move .gitattributes to the root of the project (ionic-te…

…am#29591)

Issue number: resolves N/A

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## What is the current behavior?
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## What is the new behavior?
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this was mistakenly put in the core directory in
ionic-team#29584

## Does this introduce a breaking change?

- [ ] Yes
- [X] No

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## Other information

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