[Gutenberg] Global Style Settings Analytics

[chipsnyder]

Description

This is built off of #16823 and should be merged afterwards.

These events are being registered in: https://github.com/Automattic/tracks-events-registration/pull/517

To test:

FSE Theme with /wp-block-editor/v1/settings

1. Set up a site that uses a FSE theme, and enable the GSS Settings via the debug options
2. Navigate to the editor
3. Expect to see the event wpios_editor_settings_fetched <endpoint: wp-block-editor, full_site_editing: true>

Traditional Theme with /wp-block-editor/v1/settings

1. Set up a site that is using a non-FSE theme, and enable the GSS Settings via the debug options
2. Navigate to the editor
3. Expect to see the event wpios_editor_settings_fetched <endpoint: wp-block-editor, full_site_editing: false>

Traditional Theme with /wp/v2/themes

1. Set up a site that is using a non-FSE theme, and diable the GSS Settings or select a self-hosted site with the base WP install
2. Navigate to the editor
3. Expect to see the event wpios_editor_settings_fetched <endpoint: theme_supports, full_site_editing: false>

Regression Notes

1. Potential unintended areas of impact
   N/A

2. What I did to test those areas of impact (or what existing automated tests I relied on)
   N/A

3. What automated tests I added (or what prevented me from doing so)
   This is just an analytics event change

PR submission checklist:

• I have completed the Regression Notes.
• I have considered adding unit tests for my changes.
• I have considered adding accessibility improvements for my changes.
• I have considered if this change warrants user-facing release notes and have added them to RELEASE-NOTES.txt if necessary.

[peril-wordpress-mobile]

You can trigger an installable build for these changes by visiting CircleCI here.

[peril-wordpress-mobile]

You can trigger optional UI/connected tests for these changes by visiting CircleCI here.

[antonis]

The code changes look good and the app works as expected 🎉
Great work Chip 👍