Move hagrid::web::tests::common::assert::check_maintenance() helper to hagrid::routes::tests::common::assert::maintenance::check_maintenance().

Additional changes:
- Adjust imports and usages accordingly.

src/routes/mod.rs

@@ -244,6 +244,23 @@ pub mod tests {
                 println!("{body}");
                 assert!(!body.contains(absent_page_text));
             }
+
+            pub mod maintenance {
+                use super::*;
+
+                pub fn check_maintenance(
+                    response: LocalResponse,
+                    content_type: ContentType,
+                    maintenance_text: &str,
+                ) {
+                    super::response(
+                        response,
+                        Status::ServiceUnavailable,
+                        content_type,
+                        maintenance_text,
+                    );
+                }
+            }
         }
     }
 

src/web/mod.rs

@@ -324,19 +324,6 @@ pub mod tests {
             use std::path::Path;
             use std::time::SystemTime;
 
-            pub fn check_maintenance(
-                response: LocalResponse,
-                content_type: ContentType,
-                maintenance_text: &str,
-            ) {
-                crate::routes::tests::common::assert::response(
-                    response,
-                    Status::ServiceUnavailable,
-                    content_type,
-                    maintenance_text,
-                );
-            }
-
             /// Asserts that the given URI 404s.
             pub fn check_null_response(client: &Client, uri: &str) {
                 let response = client.get(uri).dispatch();
@@ -832,39 +819,39 @@ pub mod tests {
         file.write_all(maintenance_text.as_bytes()).unwrap();
 
         // Check that endpoints return a maintenance message
-        common::assert::check_maintenance(
+        assert::maintenance::check_maintenance(
             client.get("/upload").dispatch(),
             ContentType::HTML,
             maintenance_text,
         );
-        common::assert::check_maintenance(
+        assert::maintenance::check_maintenance(
             client.get("/manage").dispatch(),
             ContentType::HTML,
             maintenance_text,
         );
-        common::assert::check_maintenance(
+        assert::maintenance::check_maintenance(
             client.get("/verify").dispatch(),
             ContentType::HTML,
             maintenance_text,
         );
-        common::assert::check_maintenance(
+        assert::maintenance::check_maintenance(
             client.get("/pks/add").dispatch(),
             ContentType::Plain,
             maintenance_text,
         );
-        common::assert::check_maintenance(
+        assert::maintenance::check_maintenance(
             client.get("/vks/v1/upload").dispatch(),
             ContentType::JSON,
             maintenance_text,
         );
-        common::assert::check_maintenance(
+        assert::maintenance::check_maintenance(
             client.get("/vks/v1/request-verify").dispatch(),
             ContentType::JSON,
             maintenance_text,
         );
 
         // Extra check for the shortcut "PUT" endpoint
-        common::assert::check_maintenance(
+        assert::maintenance::check_maintenance(
             client.put("/").dispatch(),
             ContentType::Plain,
             maintenance_text,