Font Library: Register the Google Font collection

[youknowriad]

Trac ticket: https://core.trac.wordpress.org/ticket/59166

This PR register the google fonts collection allowing users to install Google Fonts if they wish to.

Testing instructions

• Go to the site editor
• Open the global styles panel
• Open typography
• Click on the "Aa" icon to open the font library
• On the third panel, you should be able to enable google fonts and install them properly.

[github-actions]

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Props youknowriad, get_dave, mcsf.

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Co-authored-by: youknowriad <youknowriad@git.wordpress.org>
Co-authored-by: getdave <get_dave@git.wordpress.org>
Co-authored-by: mcsf <mcsf@git.wordpress.org>

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[github-actions]

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Test this pull request with WordPress Playground.

[youknowriad]

Looks like this is failing the e2e tests, it seems that the Gutenberg plugin need to "unregister" the font before registering it. We'd have to do a patch release on Gutenberg before shipping this commit to Core.

[mcsf]

Nice and easy. LGTM, tests well, but I left a suggestion.

[youknowriad]

Commit https://core.trac.wordpress.org/changeset/57558