Relocate font directory to uploads sub-directory.

[peterwilsoncc]

Per ​https://make.wordpress.org/core/2024/03/25/wordpress-6-5-release-delayed-1-week/ it's being decided to relocate font files to a sub-directory of the uploads folder following community feedback.

## What?
Default fonts directory to wp-content/uploads/fonts instead of wp-content/fonts.

## Context links:

• ​https://github.com/WordPress/gutenberg/issues/53965
• ​https://github.com/WordPress/gutenberg/issues/59417
• ​https://make.wordpress.org/core/2024/03/07/unblocking-wp6-5-font-library-and-synced-pattern-overrides/
• ​https://make.wordpress.org/core/2024/03/21/font-library-update-storage-of-font-files/
• ​https://make.wordpress.org/core/2024/03/25/wordpress-6-5-release-delayed-1-week/

---
Trac ticket: https://core.trac.wordpress.org/ticket/60845

---
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.

_Edit: Add third context link and trac ticket -- @peterwilsoncc_

[peterwilsoncc]

The ​linked pull request:

• updates the directory to uploads/fonts or the multi-site sub-site equivalent
• updates the unit tests
• adds a multisite sub-site test

It already has four committers' approval, including @davidbaumwald (WP 6.5 co-core tech lead) so is ready for commit. Self assigning to do the commit shortly.

[peterwilsoncc]

In 57878:

Editor: Relocate font files uploads to the uploads directory.

Relocate the upload of font files uploaded via the Font Library feature to the wp-content/uploads/fonts (or multisite equivalent) directory.

This accounts for immutable file systems in which directories are unable to be created within wp-content and deploy processes which require special consideration of the uploads directory to ensure it remains persistent between deploys.

Props azaozz, burnuser, cbirdsong, christopherplus, costdev, davidbaumwald, desrosj, elrae, euthelup, get_dave, grantmkin, hellofromtonya, janthiel, jazzs3quence, johnbillion, jorbin, justlevine, kraftner, matveb, mcsf, mmaattiiaass, nico23, peterwilsoncc, priethor, rmccue, samuelsidler, swissspidy, youknowriad.
Fixes #60845.

Committed r57878 / ​https://github.com/WordPress/wordpress-develop/commit/f8e1870778cadf3bd48d03fb4e53fd144686ffe9

[peterwilsoncc]

Reopening for backport consideration to the 6.5 branch.

[davidbaumwald]

Looks good to backport to the 6.5 branch. Thanks @peterwilsoncc!

[peterwilsoncc]

@davidbaumwald Thanks David, due to merge conflicts [57868] for #60652 will need to go in prior to this so I'll hold off on this for now.

[swissspidy]

In 57880:

Editor: Relocate font files uploads to the uploads directory.

Relocate the upload of font files uploaded via the Font Library feature to the wp-content/uploads/fonts (or multisite equivalent) directory.

This accounts for immutable file systems in which directories are unable to be created within wp-content and deploy processes which require special consideration of the uploads directory to ensure it remains persistent between deploys.

Reviewed by davidbaumwald.
Merges [57878] to the 6.5 branch.

Props azaozz, burnuser, cbirdsong, christopherplus, costdev, davidbaumwald, desrosj, elrae, euthelup, get_dave, grantmkin, hellofromtonya, janthiel, jazzs3quence, johnbillion, jorbin, justlevine, kraftner, matveb, mcsf, mmaattiiaass, nico23, peterwilsoncc, priethor, rmccue, samuelsidler, swissspidy, youknowriad.
Fixes #60845.