[Fix]Fluentd's s3 output plugin is compatible with minio

[vincent-vinf]

What this PR does / why we need it:

For the s3 output plugin of Fluentd, parameters are added to be compatible with minio

Which issue(s) this PR fixes:

Fixes #849

Does this PR introduced a user-facing change?

The following fields were added to the fluentd S3 output plugin
- 's3Endpoint': The endpoint URL (like "http://localhost:9000/")
- 'forcePathStyle': This prevents AWS SDK from breaking endpoint URL
- 'timeSliceFormat': This timestamp is added to each file name

Additional documentation, usage docs, etc.:

- [Usage]: [Send Apache Logs to Minio](https://docs.fluentd.org/how-to-guides/apache-to-minio)
- [Other doc]: [S3](https://docs.fluentd.org/output/s3)

[benjaminhuo]

@vincent-vinf Thank you!