FIX: crawler view with unicode usernames (#27051)

When "unicode_usernames" is enabled, calling the "user_path" helper with a username containing some non ASCII character will break due to the route constraint we have on username.

This fixes the issue by always encoding the username before passing it to the "user_path" helper.

Internal ref - t/127547

spec/requests/about_controller_spec.rb

@@ -38,6 +38,14 @@ RSpec.describe AboutController do
         expect(response.status).to eq(200)
         expect(response.body).to include("/u/anadminuser")
       end
+
+      it "supports unicode usernames" do
+        SiteSetting.unicode_usernames = true
+        Fabricate(:admin, username: "martínez")
+        get "/about", headers: { "HTTP_USER_AGENT" => "Googlebot" }
+        expect(response.status).to eq(200)
+        expect(response.body).to include("/u/mart%25C3%25ADnez")
+      end
     end
 
     it "serializes stats when 'Guardian#can_see_about_stats?' is true" do