Add endpoint to check open signup

src/api/auth.rs

@@ -86,3 +86,9 @@ pub async fn logout() -> Result<()> {
 pub async fn get_user() -> Result<Option<User>> {
     Ok(auth.user.clone().map(Into::into))
 }
+
+/// Check if open signup is enabled
+#[get("/api/v1/auth/open-signup", config: Extension<Config>)]
+pub async fn open_signup() -> Result<bool> {
+    Ok(config.auth.open_signup)
+}