Count and periodically print number of S3 operations

I'm using Cloudflare R2, which charges per million Class A or Class B operations, and it'd be really nice to be able to estimate how much each rclone run will cost by printing the count of S3 operations (ideally split into class A and B, but for starters just the total) either periodically or on every operation (controlled by a flag).

|Class A Operations|1 million requests / month|$4.50 / million requests|
|Class B Operations|10 million requests / month|$0.36 / million requests|

It would be fairly easy for rclone to count http transactions. We can already limit these per second so it would just be a single counter it the stats.

That would be useful for all backends.

Would that be useful to you?

If you can't separate them by classes for Cloudflare, then yeah, a single count would be handy regardless.

​​Class A operations

Class A Operations include ListBuckets, PutBucket, ListObjects, PutObject, CopyObject, CompleteMultipartUpload, CreateMultipartUpload, ListMultipartUploads, UploadPart, UploadPartCopy and PutBucketEncryption.

​​Class B operations

Class B Operations include HeadBucket, HeadObject, GetObject, UsageSummary, GetBucketEncryption and GetBucketLocation.

​​Free operations

Free operations include DeleteObject, DeleteBucket and AbortMultipartUpload.