Closes #5640: Wrong Home URL TranslatePress

[Miraeld]

Description

A new column is_home has been added to the our table in the database, and the logic around the creation of job has been changed.

Fixes #5640

Type of change

• Enhancement (non-breaking change which improves an existing functionality).

Is the solution different from the one proposed during the grooming?

No

Checklists

Generic development checklist

• My code follows the style guidelines of this project, with adapted comments and without new warnings.
• I have added unit and integration tests that prove my fix is effective or that my feature works.
• The CI passes locally with my changes (including unit tests, integration tests, linter).
• Any dependent changes have been merged and published in downstream modules.
• If applicable, I have made corresponding changes to the documentation. Provide a link to the documentation.

Test summary

• I triggered all changed lines of code at least once without new errors/warnings/notices.
• I validated all Acceptance Criteria of the related issues. (If applicable, provide proof).
• I validated all test plan the QA Review asked me to.

[wordpressfan]

Good job @Miraeld

for @wp-media/qa-team we need to test both translatepress and wpml.
Check this old issue for more details:
#5065

[Mai-Saad]

@Miraeld Thanks for the PR. Please find exploratory test notes below:

• The issue was not reproducible on 3.15.4. However, with the PR, the translated home language returns 404 in the used CSS. @Miraeld can you please check 🙏
  
• When updating while having already home page as completed in the used CSS, is_home will be 0 till we regenerate the used CSS for this page. @piotrbak what do you think? shall it be fixed here or is it acceptable for now?