Our `namespace` helper returns a string. However, Rails version 5.2.4.6
doesn't allow strings as arguments to polymorphic_path [1]
Since returning a symbol in our `namespace` helper would break other
places in the application, we're converting it to a symbol in the
methods calling `polymorphic_path`.
[1] https://github.com/advisories/GHSA-hjg4-8q5f-x6fm
85f13f9501