Resolve theme relative font faces uris in theme.json and style variations

[matiasbenedetto]

Resolve theme relative font faces URIs in theme.json and style variations.
Porting this change from Gutenberg repo: WordPress/gutenberg#65019

Trac ticket: https://core.trac.wordpress.org/ticket/62231

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This Pull Request is for code review only. Please keep all other discussion in the Trac ticket. Do not merge this Pull Request. See GitHub Pull Requests for Code Review in the Core Handbook for more details.

[github-actions]

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Props mmaattiiaass, ramonopoly.

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[github-actions]

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[ramonjd]

Should we close this since WordPress/gutenberg#65019 was closed?

[matiasbenedetto]

Should we close this since WordPress/gutenberg#65019 was closed?

Yes, let's close this. An alternative approach has been already merged.