Hash onion computation can exhaust node resources

[shuse2]

Expected behavior

There should be limit on number of hash computation so that memory and cpu usage is bounded.
This RPC endpoints should be only enabled per whitelist with this issue. Therefore, this endpoint should be only called from the node operator by default.

Actual behavior

With the very high number of count for the setHashOnion like below.

Steps to reproduce

Call RPC endpoint with

{"jsonrpc": "2.0", "id": 1, "method": "random_setHashOnion", "params":{"address":
"lskkgfk84gngotqjsqfujkctshvkwzs8z8w93gmja", "count": 1.7976931348623157e+308}}

Which version(s) does this affect? (Environment, OS, etc...)

6.0.0-beta.1