ui: make swapd ports configurable

[noot]

make swapd http and ws ports configurable instead of hard-coded

[dimalinux]

Can clarify the issue a little and the desired behavior? It looks like the ports are configurable already:

atomic-swap$ ./swapd --help | grep port
   --rpc-port value                port for the daemon RPC server to run on; default 5001 (default: 0)
   --ws-port value                 port for the daemon RPC websockets server to run on; default 8080 (default: 0)
   --libp2p-port value             libp2p port to listen on (default: 0)

I can see above that there is an issue with how the values are defaulted. Setting the default value correctly in the argument parsing code to the stated (above) value is a trivial change, but it looks like the default value is actually dependent on other flags:

	p = uint16(c.Uint(flagRPCPort))
	switch {
	case p != 0:
		rpcPort = p
	case devXMRTaker:
		rpcPort = defaultXMRTakerRPCPort
	case devXMRMaker:
		rpcPort = defaultXMRMakerRPCPort
	default:
		rpcPort = defaultRPCPort
	}

	wsPort := uint16(c.Uint(flagWSPort))
	switch {
	case wsPort != 0:
	case devXMRTaker:
		wsPort = defaultXMRTakerWSPort
	case devXMRMaker:
		wsPort = defaultXMRMakerWSPort
	default:
		wsPort = defaultWSPort
	}

[noot]

hey @dimalinux , the issue is referencing the port for the UI only. currently it's hard-coded to send RPC calls to http://localhost:5001, see here: https://github.com/noot/atomic-swap/blob/master/ui/src/utils/rpcApi.ts#L12

the intended behaviour is to have the UI select what port to use based on some env variable, falling back to 5001 if it's not set.