Revert "deprecate embedded browser (#12163)"

This reverts commit 736d8cbac4.

Bring contrib files for older contributions

cmd/generic-handlers_contrib.go

@@ -0,0 +1,32 @@
+/*
+ * MinIO Object Storage (c) 2021 MinIO, Inc.
+ *
+ * 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.
+ */
+
+package cmd
+
+import (
+	"net/http"
+	"strings"
+)
+
+// guessIsLoginSTSReq - returns true if incoming request is Login STS user
+func guessIsLoginSTSReq(req *http.Request) bool {
+	if req == nil {
+		return false
+	}
+	return strings.HasPrefix(req.URL.Path, loginPathPrefix) ||
+		(req.Method == http.MethodPost && req.URL.Path == SlashSeparator &&
+			getRequestAuthType(req) == authTypeSTS)
+}