feat(iam): add SetUserStatus and UpdateAccessKey actions (#7750)

feat(iam): add SetUserStatus and UpdateAccessKey actions (#7745)

Add ability to enable/disable users and access keys without deleting them.

## Changes

### Protocol Buffer Updates
- Add `disabled` field (bool) to Identity message for user status
  - false (default) = enabled, true = disabled
  - No backward compatibility hack needed since zero value is correct
- Add `status` field (string: Active/Inactive) to Credential message

### New IAM Actions
- SetUserStatus: Enable or disable a user (requires admin)
- UpdateAccessKey: Change access key status (self-service or admin)

### Behavior
- Disabled users: All API requests return AccessDenied
- Inactive access keys: Signature validation fails
- Status check happens early in auth flow for performance
- Backward compatible: existing configs default to enabled (disabled=false)

### Use Cases
1. Temporary suspension: Disable user access during investigation
2. Key rotation: Deactivate old key before deletion
3. Offboarding: Disable rather than delete for audit purposes
4. Emergency response: Quickly disable compromised credentials

Fixes #7745

weed/s3api/s3api_bucket_handlers_test.go

@@ -670,7 +670,7 @@ func TestListBucketsIssue7647(t *testing.T) {
 	t.Run("admin user can see their created buckets", func(t *testing.T) {
 		// Simulate the exact scenario from issue #7647:
 		// User "root" with ["Admin", "Read", "Write", "Tagging", "List"] permissions
-		
+
 		// Create identity for root user with Admin action
 		rootIdentity := &Identity{
 			Name: "root",
@@ -730,7 +730,7 @@ func TestListBucketsIssue7647(t *testing.T) {
 	t.Run("admin user sees buckets without owner metadata", func(t *testing.T) {
 		// Admin users should see buckets even if they don't have owner metadata
 		// (this can happen with legacy buckets or manual creation)
-		
+
 		rootIdentity := &Identity{
 			Name: "root",
 			Actions: []Action{
@@ -754,7 +754,7 @@ func TestListBucketsIssue7647(t *testing.T) {
 
 	t.Run("non-admin user cannot see buckets without owner", func(t *testing.T) {
 		// Non-admin users should not see buckets without owner metadata
-		
+
 		regularUser := &Identity{
 			Name: "user1",
 			Actions: []Action{