[#100] preset_s3: Add a flag for percent of versioned buckets

Add flag "--buckets_versioned". Default is 0 (no versioned buckets)

Signed-off-by: Nikita Zinkevich <n.zinkevich@yadro.com>

internal/s3/client.go

@@ -142,6 +142,8 @@ func (c *Client) Get(bucket, key string) GetResponse {
 	return GetResponse{Success: true}
 }
 
+// DeleteObjectVersion deletes object version with specified versionID.
+// If version argument is empty, deletes all versions and delete-markers of specified object.
 func (c *Client) DeleteObjectVersion(bucket, key, version string) DeleteResponse {
 	var toDelete []types.ObjectIdentifier