Rewrite @automattic/global-styles to align with Calypso's React 18 upgrade

[taipeicoder]

Related issue: #77046

Description

There is an ongoing effort to upgrade Calypso to React 18. WordPress packages will also be updated to the first version that supports React 18. As a result, the package @automatic/global-styles will be heavily affected since it has a lot of hard dependencies with WordPress packages, especially @wordpress/edit-site.

Please refer to this discussion for more context: p1684368118561169-slack-CRWCHQGUB

Acceptance Criteria

• Rewrite @automattic/global-styles using the WordPress packages updated in React 18 #77046.
• (Optional) Avoid importing from the build_module path. Please make a separate issue if it's going to be a follow-up task.

[arthur791004]

Here are the functions we need to rewrite (commit):

• GlobalStylesContext
• mergeBaseAndUserConfigs
• useSettings
• useStyle
• useGlobalStylesOutput

[arthur791004]

Closing it via #77319. Will draft a p2 to describe how it works!