feat(client-redirects): make plugin respect onDuplicateRoutes config

[Josh-Cena]

Pre-flight checklist

• I have read the Contributing Guidelines on pull requests.
• If this is a code change: I have written unit tests and/or added dogfooding pages to fully verify the new behavior.
• If this is a new API or substantial change: the PR has an accompanying issue (closes plugin-client-redirects error should return non-zero code on build #7615) and the maintainers have approved on my working plan.

Motivation

Test Plan

Test links

Deploy preview: https://deploy-preview-_____--docusaurus-2.netlify.app/

Related issues/PRs

[netlify]

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[github-actions]

⚡️ Lighthouse report for the deploy preview of this PR

URL	Performance	Accessibility	Best Practices	SEO	PWA	Report
/	🟠 71	🟢 100	🟢 100	🟢 100	🟢 90	Report
/docs/installation	🟠 87	🟢 100	🟢 100	🟢 100	🟢 90	Report

[github-actions]

Size Change: 0 B

Total Size: 801 kB

ℹ️ View Unchanged

Filename	Size
website/.docusaurus/globalData.json	52.6 kB
website/build/assets/css/styles.********.css	106 kB
website/build/assets/js/main.********.js	603 kB
website/build/index.html	38.9 kB

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[slorber]

LGTM 👍