Refactor: Extract common IAM logic into shared weed/iam package (#7747)

This resolves GitHub issue #7747 by extracting duplicated IAM code into
a shared package that both the embedded S3 IAM and standalone IAM use.

New shared package (weed/iam/):
- constants.go: Common constants (charsets, action strings, error messages)
- helpers.go: Shared helper functions (Hash, GenerateRandomString,
  GenerateAccessKeyId, GenerateSecretAccessKey, StringSlicesEqual,
  MapToStatementAction, MapToIdentitiesAction, MaskAccessKey)
- responses.go: Common IAM response structs (CommonResponse, ListUsersResponse,
  CreateUserResponse, etc.)
- helpers_test.go: Unit tests for shared helpers

Updated files:
- weed/s3api/s3api_embedded_iam.go: Use type aliases and function wrappers
  to the shared package, removing ~200 lines of duplicated code
- weed/iamapi/iamapi_management_handlers.go: Use shared package for constants
  and helper functions, removing ~100 lines of duplicated code
- weed/iamapi/iamapi_response.go: Re-export types from shared package for
  backwards compatibility

Benefits:
- Single source of truth for IAM constants and helpers
- Easier maintenance - changes only need to be made in one place
- Reduced risk of inconsistencies between embedded and standalone IAM
- Better test coverage through shared test suite

1 files changed, 21 insertions, 108 deletions

diff --git a/weed/iamapi/iamapi_response.go b/weed/iamapi/iamapi_response.go
index fc68ce5a5..c16b1f79b 100644
--- a/weed/iamapi/iamapi_response.go
+++ b/weed/iamapi/iamapi_response.go
@@ -1,113 +1,26 @@
 package iamapi
 
-import (
-	"encoding/xml"
-	"fmt"
-	"time"
+// This file re-exports IAM response types from the shared weed/iam package
+// for backwards compatibility with existing code.
 
-	"github.com/aws/aws-sdk-go/service/iam"
+import (
+	iamlib "github.com/seaweedfs/seaweedfs/weed/iam"
 )
 
-type CommonResponse struct {
-	ResponseMetadata struct {
-		RequestId string `xml:"RequestId"`
-	} `xml:"ResponseMetadata"`
-}
-
-type ListUsersResponse struct {
-	CommonResponse
-	XMLName         xml.Name `xml:"https://iam.amazonaws.com/doc/2010-05-08/ ListUsersResponse"`
-	ListUsersResult struct {
-		Users       []*iam.User `xml:"Users>member"`
-		IsTruncated bool        `xml:"IsTruncated"`
-	} `xml:"ListUsersResult"`
-}
-
-type ListAccessKeysResponse struct {
-	CommonResponse
-	XMLName              xml.Name `xml:"https://iam.amazonaws.com/doc/2010-05-08/ ListAccessKeysResponse"`
-	ListAccessKeysResult struct {
-		AccessKeyMetadata []*iam.AccessKeyMetadata `xml:"AccessKeyMetadata>member"`
-		IsTruncated       bool                     `xml:"IsTruncated"`
-	} `xml:"ListAccessKeysResult"`
-}
-
-type DeleteAccessKeyResponse struct {
-	CommonResponse
-	XMLName xml.Name `xml:"https://iam.amazonaws.com/doc/2010-05-08/ DeleteAccessKeyResponse"`
-}
-
-type CreatePolicyResponse struct {
-	CommonResponse
-	XMLName            xml.Name `xml:"https://iam.amazonaws.com/doc/2010-05-08/ CreatePolicyResponse"`
-	CreatePolicyResult struct {
-		Policy iam.Policy `xml:"Policy"`
-	} `xml:"CreatePolicyResult"`
-}
-
-type CreateUserResponse struct {
-	CommonResponse
-	XMLName          xml.Name `xml:"https://iam.amazonaws.com/doc/2010-05-08/ CreateUserResponse"`
-	CreateUserResult struct {
-		User iam.User `xml:"User"`
-	} `xml:"CreateUserResult"`
-}
-
-type DeleteUserResponse struct {
-	CommonResponse
-	XMLName xml.Name `xml:"https://iam.amazonaws.com/doc/2010-05-08/ DeleteUserResponse"`
-}
-
-type GetUserResponse struct {
-	CommonResponse
-	XMLName       xml.Name `xml:"https://iam.amazonaws.com/doc/2010-05-08/ GetUserResponse"`
-	GetUserResult struct {
-		User iam.User `xml:"User"`
-	} `xml:"GetUserResult"`
-}
-
-type UpdateUserResponse struct {
-	CommonResponse
-	XMLName xml.Name `xml:"https://iam.amazonaws.com/doc/2010-05-08/ UpdateUserResponse"`
-}
-
-type CreateAccessKeyResponse struct {
-	CommonResponse
-	XMLName               xml.Name `xml:"https://iam.amazonaws.com/doc/2010-05-08/ CreateAccessKeyResponse"`
-	CreateAccessKeyResult struct {
-		AccessKey iam.AccessKey `xml:"AccessKey"`
-	} `xml:"CreateAccessKeyResult"`
-}
-
-type PutUserPolicyResponse struct {
-	CommonResponse
-	XMLName xml.Name `xml:"https://iam.amazonaws.com/doc/2010-05-08/ PutUserPolicyResponse"`
-}
-
-type DeleteUserPolicyResponse struct {
-	CommonResponse
-	XMLName xml.Name `xml:"https://iam.amazonaws.com/doc/2010-05-08/ DeleteUserPolicyResponse"`
-}
-
-type GetUserPolicyResponse struct {
-	CommonResponse
-	XMLName             xml.Name `xml:"https://iam.amazonaws.com/doc/2010-05-08/ GetUserPolicyResponse"`
-	GetUserPolicyResult struct {
-		UserName       string `xml:"UserName"`
-		PolicyName     string `xml:"PolicyName"`
-		PolicyDocument string `xml:"PolicyDocument"`
-	} `xml:"GetUserPolicyResult"`
-}
-
-type ErrorResponse struct {
-	CommonResponse
-	XMLName xml.Name `xml:"https://iam.amazonaws.com/doc/2010-05-08/ ErrorResponse"`
-	Error   struct {
-		iam.ErrorDetails
-		Type string `xml:"Type"`
-	} `xml:"Error"`
-}
-
-func (r *CommonResponse) SetRequestId() {
-	r.ResponseMetadata.RequestId = fmt.Sprintf("%d", time.Now().UnixNano())
-}
+// Type aliases for IAM response types from shared package
+type (
+	CommonResponse          = iamlib.CommonResponse
+	ListUsersResponse       = iamlib.ListUsersResponse
+	ListAccessKeysResponse  = iamlib.ListAccessKeysResponse
+	DeleteAccessKeyResponse = iamlib.DeleteAccessKeyResponse
+	CreatePolicyResponse    = iamlib.CreatePolicyResponse
+	CreateUserResponse      = iamlib.CreateUserResponse
+	DeleteUserResponse      = iamlib.DeleteUserResponse
+	GetUserResponse         = iamlib.GetUserResponse
+	UpdateUserResponse      = iamlib.UpdateUserResponse
+	CreateAccessKeyResponse = iamlib.CreateAccessKeyResponse
+	PutUserPolicyResponse   = iamlib.PutUserPolicyResponse
+	DeleteUserPolicyResponse = iamlib.DeleteUserPolicyResponse
+	GetUserPolicyResponse   = iamlib.GetUserPolicyResponse
+	ErrorResponse           = iamlib.ErrorResponse
+)