Proxito: refactor CDNCacheTagsMixin

[stsewd]

When I wrote this mixin, it was to re-use it in the footer, search and related views where the project and version are given in the URL

readthedocs.org/readthedocs/api/mixins.py

Line 14 in 8c462bd

class CDNCacheTagsMixin:

But now we have views that are a little more complex on how they extract the project and version, and even ones that don't map to a version. All proxito views do map to at least one version (the one that belongs to the domain), so we can start with that being the default, probably.

This is kind of related to these attributes that we pass from several views to the middleware

readthedocs.org/readthedocs/proxito/middleware.py

Lines 51 to 52 in 8c462bd

	project_slug = getattr(request, 'path_project_slug', '')
	version_slug = getattr(request, 'path_version_slug', '')

(they are used to set the cache tags!)

Haven't thought of a solution yet, but just wanted to open an issue, so we don't forget.