Use RPC to get the port instead of parsing the argument

Currently, the client thinks the port of the node is 3485 if there is no argument.
https://github.com/CodeChain-io/codechain-dashboard/blob/2f061c27b74d44f1c4488e88a1d91c1640078c6a/client/src/process/mod.rs#L622
However, the port can be set through config.toml.
Please make it use `net_port` RPC.

Start at client/src/process/mod.rs around line 622 and inspect how the client determines the node port when no argument is provided. Use the net_port RPC instead of the default assumption, and verify that the client uses the configured node port.

索引モデルが issue の本文から書いたものです。