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_action_resolver.go

@@ -289,8 +289,8 @@ func resolveBucketLevelAction(method string, baseAction string) string {
 // mapBaseActionToS3Format converts coarse-grained base actions to S3 format
 // This is the fallback when no specific resolution is found
 func mapBaseActionToS3Format(baseAction string) string {
-	// Handle actions that already have s3: prefix
-	if strings.HasPrefix(baseAction, "s3:") {
+	// Handle actions that already have s3: or iam: prefix
+	if strings.HasPrefix(baseAction, "s3:") || strings.HasPrefix(baseAction, "iam:") {
 		return baseAction
 	}