Include ServerSideEncryption in _info() output

[belegdol]

Hello,

currently _info() function returns a subset of S3 object properties:

s3fs/s3fs/core.py

Lines 1749 to 1756 in 609950a

	"ETag": out.get("ETag", ""),
	"LastModified": out.get("LastModified", ""),
	"size": out["ContentLength"],
	"name": "/".join([bucket, key]),
	"type": "file",
	"StorageClass": out.get("StorageClass", "STANDARD"),
	"VersionId": out.get("VersionId"),
	"ContentType": out.get("ContentType"),

In particular, ServerSideEncryption is missing, which makes it hard to check whether ETag is supposed to contain MD5 checksums. Would it be possible to include it? Thanks!

[martindurant]

I would happily consider a PR for this; I'm not sure when I would have time to do it myself.