S3: Enforce bucket policy (#7471)

* evaluate policies during authorization

* cache bucket policy

* refactor

* matching with regex special characters

* Case Sensitivity, pattern cache, Dead Code Removal

* Fixed Typo, Restored []string Case, Added Cache Size Limit

* hook up with policy engine

* remove old implementation

* action mapping

* validate

* if not specified, fall through to IAM checks

* fmt

* Fail-close on policy evaluation errors

* Explicit `Allow` bypasses IAM checks

* fix error message

* arn:seaweed => arn:aws

* remove legacy support

* fix tests

* Clean up bucket policy after this test

* fix for tests

* address comments

* security fixes

* fix tests

* temp comment out

test/s3/iam/README-Docker.md

@@ -170,7 +170,7 @@ The `setup_keycloak_docker.sh` script automatically generates `iam_config.json`
 {
   "claim": "roles",
   "value": "s3-admin", 
-  "role": "arn:seaweed:iam::role/KeycloakAdminRole"
+  "role": "arn:aws:iam::role/KeycloakAdminRole"
 }
 ```