improve internal item counter mechanisms and implement bucket quotas (#326)

- [x] Refactoring of internal counting API
- [x] Repair procedure for counters (it's an offline procedure!!!)
- [x] New counter for objects in buckets
- [x] Add quotas to buckets struct
- [x] Add CLI to manage bucket quotas
- [x] Add admin API to manage bucket quotas
- [x] Apply quotas by adding checks on put operations
- [x] Proof-read

Co-authored-by: Alex Auvolat <alex@adnab.me>
Reviewed-on: https://git.deuxfleurs.fr/Deuxfleurs/garage/pulls/326
Co-authored-by: Alex <alex@adnab.me>
Co-committed-by: Alex <alex@adnab.me>

src/garage/cli/cmd.rs

@@ -169,8 +169,12 @@ pub async fn cmd_admin(
 		AdminRpc::BucketList(bl) => {
 			print_bucket_list(bl);
 		}
-		AdminRpc::BucketInfo(bucket, rk) => {
-			print_bucket_info(&bucket, &rk);
+		AdminRpc::BucketInfo {
+			bucket,
+			relevant_keys,
+			counters,
+		} => {
+			print_bucket_info(&bucket, &relevant_keys, &counters);
 		}
 		AdminRpc::KeyList(kl) => {
 			print_key_list(kl);