S3: set identity to request context, and remove obsolete code (#7523)

* list owned buckets

* simplify

* add unit tests

* no-owner buckets

* set identity id

* fallback to request header if iam is not enabled

* refactor to test

* fix comparing

* fix security vulnerability

* Update s3api_bucket_handlers.go

* Update s3api_bucket_handlers.go

* Update s3api_bucket_handlers.go

* set identity to request context

* remove SeaweedFSIsDirectoryKey

* remove obsolete

* simplify

* reuse

* refactor or remove obsolete logic on filer

* Removed the redundant check in GetOrHeadHandler

* surfacing invalid X-Amz-Tagging as a client error

* clean up

* constant

* reuse

* multiple header values

* code reuse

* err on duplicated tag key

weed/s3api/auth_credentials.go

@@ -421,8 +421,10 @@ func (iam *IdentityAccessManagement) Auth(f http.HandlerFunc, action Action) htt
 		glog.V(3).Infof("auth error: %v", errCode)
 
 		if errCode == s3err.ErrNone {
+			// Store the authenticated identity in request context (secure, cannot be spoofed)
 			if identity != nil && identity.Name != "" {
-				r.Header.Set(s3_constants.AmzIdentityId, identity.Name)
+				ctx := s3_constants.SetIdentityNameInContext(r.Context(), identity.Name)
+				r = r.WithContext(ctx)
 			}
 			f(w, r)
 			return