[Feature Request] Add support for timezone on Windows Events collect log

The Microsoft Windows CloudWatch agent does not support the `timezone` property within the Windows Event Log collect list unlike the generic log collect list.

**Desired Configuration**
```
"windows_events": {
"collect_list": [
{
"event_format": "xml",
"event_levels": [
"INFORMATION",
"WARNING",
"ERROR",
"CRITICAL"
],
"event_name": "Application",
"log_group_name": "/c/windows/system32/winevt/logs/application",
"timezone": "UTC"
}
]
}
```

The CloudWatch agent service being unable to start with the Log file for the local Windows instance when the timezone property is specified within the `windows_event` property:
```
2020/08/27 14:03:27 Under path : /logs/logs_collected/windows_events/collect_list/0 | Error : Additional property timezone is not allowed".
```

Start by finding the Windows Events collect_list schema and the existing generic log collect_list handling for timezone. Confirm the configuration accepts the property without the reported validation error and verify Windows event timestamps use the requested timezone.

Written by the indexing model from the issue text.