Ability to configure a custom SOCKS proxy

[giomasce]

Hi, first of all thanks for your really nice application!

An improvement that would be really useful for me would be to be able to set a custom SOCKS proxy. AFAIU Grocy Android already supports a SOCKS proxy, but that's hardwired to a locally-running Orbot instance. Being able to choose the address and port, like is already possible with the HTTP proxy, would be a great plus for me.

Thanks again!