File permissions can't have full accesss

### Describe the bug

Unable to set

file_permission 777

Files are created as 755 due to umask.

### To Reproduce

add to config:

file_permission 777

### Expected behavior

files should be created with full permissions

### Your Environment

```markdown
- Fluentd version: v1.16.6-debian-1.0
- Operating system:GNU/Linux
- Kernel version:3.10.0-1160.76.1.el7.x86_64
```

### Your Configuration

```apache

file_permission 777

@type forward
port 24224
bind 0.0.0.0

@type copy


@type file
path /app/log/webui-testing/webui-debug-log3
append true
format out_file

path /app/buffer/webui/webui-debug-buffer
flush_interval 5s
flush_mode interval
chunk_limit_size 512m
total_limit_size 1g
overflow_action block
@type file

```

### Your Error Log

```shell
NO error message,

Files are created with r-x permissions (755) due to the default umask.
```

### Additional context

If changing the permissions is not possible how can we change the default umask?