refactor: route notify dispatch through app context (#3789)

* refactor: route notify dispatch through app context

* refactor: route admin IAM globals through app context (#3791)

* refactor: centralize IAM root credential access (#3792)

crates/iam/src/root_credentials.rs

@@ -0,0 +1,31 @@
+// Copyright 2024 RustFS Team
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use rustfs_credentials::{Credentials, get_global_action_cred};
+
+pub(crate) fn credentials() -> Option<Credentials> {
+    get_global_action_cred()
+}
+
+pub(crate) fn credentials_or_default() -> Credentials {
+    credentials().unwrap_or_default()
+}
+
+pub(crate) fn token_signing_key() -> Option<String> {
+    credentials().map(|cred| cred.secret_key)
+}
+
+pub(crate) fn is_root_access_key(access_key: &str) -> bool {
+    credentials().is_some_and(|cred| cred.access_key == access_key)
+}