Add AWS IAM integration tests and refactor admin authorization (#8098)

* Add AWS IAM integration tests and refactor admin authorization
- Added AWS IAM management integration tests (User, AccessKey, Policy)
- Updated test framework to support IAM client creation with JWT/OIDC
- Refactored s3api authorization to be policy-driven for IAM actions
- Removed hardcoded role name checks for admin privileges
- Added new tests to GitHub Actions basic test matrix

* test(s3/iam): add UpdateUser and UpdateAccessKey tests and fix nil pointer dereference

* feat(s3api): add DeletePolicy and update tests with cleanup logic

* test(s3/iam): use t.Cleanup for managed policy deletion in CreatePolicy test

weed/s3api/s3_iam_middleware.go

@@ -341,6 +341,11 @@ type MockAssumedRoleUser struct {
 
 // buildS3ResourceArn builds an S3 resource ARN from bucket and object
 func buildS3ResourceArn(bucket string, objectKey string) string {
+	// If bucket is already an ARN, return it as-is
+	if strings.HasPrefix(bucket, "arn:") {
+		return bucket
+	}
+
 	if bucket == "" {
 		return "arn:aws:s3:::*"
 	}