[web/js] Deprecate baseuri() and replace with BASE_URL (closes #3955372)
Added by commit 8bf2337a6f3b and publicly available since 3.11.2
released more than 3 years ago.
[request] Ensure base_url() always has a trailing '/' (closes #3955093)
Just as an example, cubicweb.ajax.js is clearly written under the
assumption that BASE_URL/baseuri() - which simply contains req.base_url() - has a
trailing /.