Interop: op-supervisor: Make RPC client options configurable

[ajsutton]

Add CLI options to configure the RPC client options e.g.

const epochPollInterval = 30 * time.Second
const pollInterval = 2 * time.Second
const trustRpc = false
const rpcKind = sources.RPCKindStandard

Or for those that don't need to be configurable, confirm that the value used is reasonable.