Add Brave Sync to Desktop and Mobile Brave cards

[matchboxbananasynergy]

This PR adds a mention of Brave Sync to our desktop and mobile Brave recommendation cards as it provides an E2EE way to sync bookmarks etc. without requiring an account, which makes it more privacy-respecting than even Firefox Sync, which we already mention.

Discussion: https://discuss.privacyguides.org/t/add-brave-sync/257

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[github-actions]

🎊 PR Preview 3be1a27 has been successfully built and deployed to https://privacyguides-privacyguides-org-preview-pr-1847.surge.sh

🕐 Build time: 75.114s

_{🤖 By surge-preview}

[privacyguides-bot]

This pull request has been mentioned on Privacy Guides. There might be relevant details there:

https://discuss.privacyguides.org/t/add-brave-sync/257/7

[KaiTebay]

This looks good to me. 👍

[privacyguides-bot]

This pull request has been mentioned on Privacy Guides. There might be relevant details there:

https://discuss.privacyguides.net/t/v2-28/8091/1