feat(dynamic-link)!: remove dynamic link from repository

[Lyokone]

Description

Fully removes the Dynamic Link package and adds a README to the root of the folder.

https://firebase.google.com/support/dynamic-links-faq

Related Issues

#17550

Checklist

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• I read the Contributor Guide and followed the process outlined there for submitting PRs.
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• I updated/added relevant documentation (doc comments with ///).
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Breaking Change

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• Yes, this is a breaking change.
• No, this is not a breaking change.