Create separate documentation scoring criteria for Japanese

[hannaw93]

Context

After this older PR was merged, the scoring documentation for all assessments that live inside the yoastseo package were placed inside the yoastseo package.
The Japanese scoring criteria was included in the default scoring documentation and on [the Confluence page ](Confluence page. This change removes the Japanese scoring documentation from the Confluence page and adds it instead to the yoastseo package, in separate files for more clarity and a more neat organisation.

Summary

This PR can be summarized in the following changelog entry:

• Moves the Japanese scoring documentation to the yoastseo package.

Relevant technical choices:

• This documentation does not include the feedback strings written in Japanese. If upon review it is decided that it is better to add the feedback strings in Japanese, it can be done after the first review.
• The documentation added in this PR will be removed from Confluence after the CR. If we stick to not adding the feedback strings in Japanese to the yoastseo package, the documentation will stay, but will be re-located and used to to check what feedback strings are available in Japanese then the scoring criteria.
• A link was added on Confluence to the relevant files in the yoastseo package.

Test instructions

Test instructions for the acceptance test before the PR gets merged

This PR can be acceptance tested by following these steps:

Relevant test scenarios

• Changes should be tested with the browser console open
• Changes should be tested on different posts/pages/taxonomies/custom post types/custom taxonomies
• Changes should be tested on different editors (Default Block/Gutenberg/Classic/Elementor/other)
• Changes should be tested on different browsers
• Changes should be tested on multisite

Test instructions for QA when the code is in the RC

• QA should use the same steps as above.

QA can test this PR by following these steps:

Impact check

This PR affects the following parts of the plugin, which may require extra testing:

Other environments

• This PR also affects Shopify. I have added a changelog entry starting with [shopify-seo], added test instructions for Shopify and attached the Shopify label to this PR.
• This PR also affects Yoast SEO for Google Docs. I have added a changelog entry starting with [yoast-doc-extension], added test instructions for Yoast SEO for Google Docs and attached the Google Docs Add-on label to this PR.

Documentation

• I have written documentation for this change. For example, comments in the Relevant technical choices, comments in the code, documentation on Confluence / shared Google Drive / Yoast developer portal, or other.

Quality assurance

• I have tested this code to the best of my abilities.
• During testing, I had activated all plugins that Yoast SEO provides integrations for.
• I have added unit tests to verify the code works as intended.
• If any part of the code is behind a feature flag, my test instructions also cover cases where the feature flag is switched off.
• I have written this PR in accordance with my team's definition of done.
• I have checked that the base branch is correctly set.
• I have run grunt build:images and committed the results, if my PR introduces or edits images or SVGs.

Innovation

• No innovation project is applicable for this PR.
• This PR falls under an innovation project. I have attached the innovation label.
• I have added my hours to the WBSO document.

Fixes #https://github.com/orgs/Yoast/projects/94/views/1?pane=issue&itemId=143440138&issue=Yoast%7CLingo-AI%7C2

[coveralls]

Coverage Report for CI Build 57082

Coverage remained the same at 53.944%

Details

• Coverage remained the same as the base build.
• Patch coverage: No coverable lines changed in this PR.
• No coverage regressions found.

Uncovered Changes

No uncovered changes found.

Coverage Regressions

No coverage regressions found.

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Coverage Stats

Relevant Lines:	68231
Covered Lines:	36613
Line Coverage:	53.66%
Relevant Branches:	17052
Covered Branches:	9392
Branch Coverage:	55.08%
Branches in Coverage %:	Yes
Coverage Strength:	44087.39 hits per line

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💛 - Coveralls