Closes #7181 fonts data collection

[remyperona]

Description

Fixes #7181

Collect fonts data weekly

Type of change

• Sub-task of Host Google Fonts Locally #7039

Detailed scenario

With self-host google fonts and analytics enabled, fonts data should be collected and sent to mixpanel.

data collected is stored in a transient rocket_fonts_data_collection for a week.

Technical description

Documentation

If the options are enabled, and the transient is not yet set, with recursively look into the cache/fonts/blog_id/google-fonts/fonts/ folder to count all fonts and and the total size.

Mandatory Checklist

Code validation

• I validated all the Acceptance Criteria. If possible, provide screenshots or videos.
• I triggered all changed lines of code at least once without new errors/warnings/notices.
• I implemented built-in tests to cover the new/changed code.

Code style

• I wrote a self-explanatory code about what it does.
• I protected entry points against unexpected inputs.
• I did not introduce unnecessary complexity.

Additional Checks

• In the case of complex code, I wrote comments to explain it.

[codacy-production]

Coverage summary from Codacy

See diff coverage on Codacy

Coverage variation	Diff coverage
✅ +0.05% (target: -0.10%)	✅ 72.22% (target: 50.00%)

Coverage variation details

	Coverable lines	Covered lines	Coverage
Common ancestor commit (a60bcda)	38667	17085	44.18%
Head commit (a8a6048)	38713 (+46)	17123 (+38)	44.23% (+0.05%)

Coverage variation is the difference between the coverage for the head and common ancestor commits of the pull request branch: <coverage of head commit> - <coverage of common ancestor commit>

Diff coverage details

	Coverable lines	Covered lines	Diff coverage
Pull request (#7199)	54	39	72.22%

Diff coverage is the percentage of lines that are covered by tests out of the coverable lines that the pull request added or modified: <covered lines added or modified>/<coverable lines added or modified> * 100%

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_{Codacy stopped sending the deprecated coverage status on June 5th, 2024. Learn more}

[Mai-Saad]

For testing:
1- share screenshot of collected data (as per acceptance criteria) at Mixpanel to be approved by @wp-media/product
2- While transient is set and not expired, with new pages with new GF, no new calculations/ data are sent to Mixpanel
3- confirm that if the transient is deleted manually, data will be recollected /resent

[wordpressfan]

Do we need to mention this to the user in the following two views?

to tell the user what we track.
cc @wp-media/product