Customize the IPs and private keys

[KusakabeShi]

I want an option to customize the IPs and wireguard keys for em_proxy while initialization.

Add 4 new optional paramater for em_proxy:

Name	Default Value
em_proxy server_privatekey	UI+sCDEketXDq6vOAidLe0mYiHogMh1TA2zg3CqlxEA=
em_proxy client_publickey	ow01dGyrgRSrjln9bGb6fx0FwY5XKSVMTaoKQ2GDSkM=
em_proxy server_ip	10.0.7.1
em_proxy client_ip	10.0.7.10

make these value customizable instead of hardcoded in em_prixy