[Umbrella] Unify line endings to LF & add CRLF check workflow

[zhzhuang-zju]

What would you like to be added:

1. Normalize all line endings in the karmada-website repository from CRLF to LF to unify file formats.
2. Add a GitHub Actions workflow to detect newly introduced CRLF line endings in pull requests to prevent regression.
   The command git grep --cached -I $'\r' can be used to check for carriage returns in committed text files.

Tasks:

• Eliminate CRLF line endings on the main branch (@MilindRastogi24 Normalize line endings to LF and add .gitattributes #1027)
• Eliminate CRLF line endings on the release-1.18 branch
• Eliminate CRLF line endings on the release-1.17 branch
• Eliminate CRLF line endings on the release-1.16 branch
• Add a GitHub Actions workflow to detect CRLF line endings

Why is this needed:
Some documents in the karmada-website repo use CRLF line endings instead of LF.

1. Inconsistent line endings bring messy file formatting across the whole repository.
2. CRLF may trigger unexpected behaviors of the cherrypicker plugin when backporting changes between branches. see [cherrypicker]: reports a false conflict although the change applies cleanly kubernetes-sigs/prow#745

[zhzhuang-zju]

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[karmada-bot]

@zhzhuang-zju:
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[MilindRastogi24]

@zhzhuang-zju Can I work on this issue ?

[zhzhuang-zju]

Eliminate CRLF line endings on the main branch

Thanks @MilindRastogi24. I will assign this one to you. Upon completion, you may proceed with the next task.

[MilindRastogi24]

@zhzhuang-zju I have add the PR for the main branch and now adding PR for other branches also