Redirects on subprojects do not work

[humitos]

Due to the way we get the project.slug from the request object (set by the SubdomainMiddleware), redirects instances for subprojects are never catched.

At this point,

readthedocs.org/readthedocs/redirects/utils.py

Lines 86 to 88 in c91b332

	path, http_status = project.redirects.get_redirect_path_with_status(
	path=path, language=language, version_slug=version_slug
	)

project is the superproject instead of the subproject, and all the redirect instanced defined in the subproject are completely omited.

This is strongly related to #5557. We need to refactor the middleware and set the subproject.slug into the request object to make these things to work properly.

[Abhi-khandelwal]

Hi @humitos, Can I work on this issue ?

[stsewd]

@Abhi-khandelwal sure

[Abhi-khandelwal]

@humitos Can you help me with refactoring in the middleware ?

[stsewd]

Looks like the linked code is prior to proxito, we now catch the redirects from the subproject, but not as users would expect, tracking that problem in #10049.