Support bulk loading from S3 compatible distributed storage

[yingfeng]

S3 compatible is more and more prevalent especially for cloud native applications, as a result, it's reasonable to encapsulate a S3 compatible wrapper to fs_broker to make Palo more popular on multiple clouds.

[bigdata86]

good idea

[maruyue]

这个在下一个版本，我们会开发引入

[imay]

This is supported through #3003