feat(config,cache/s3proxy): add s3 addressing style support

[wuhuizuo]

Some S3 providers do not support auto bucket lookup type, need to set it with path type or dns type.

Here I added a support to set it in s3_proxy filed in configuration to make it reachable.

[wuhuizuo]

/reopen to rerun the golang ci lint job

[mostynb]

Thanks for the contribution. Sorry it took me a few days to look at this.

[wuhuizuo]

Thanks for the contribution. Sorry it took me a few days to look at this.

I fixed it.

[mostynb]

This feature looks good to me, but I think we should use string flags instead, for improved readability.

I had to do some background reading to understand the use case. This blog post was useful, sharing it here for anyone reading through this PR later: https://aws.amazon.com/blogs/aws/amazon-s3-path-deprecation-plan-the-rest-of-the-story/

[mostynb]

I think this function should probably check if typeStr is in the map, and return an error if it isn't. And this error checking should be done in validateConfig() in config/config.go

[wuhuizuo]

I think we only need to check it in validateConfig().

[wuhuizuo]

Also I refactored it again.

[mostynb]

Thanks for following through with these changes- I made a few minor tweaks and landed this on the master branch.