add getter for daemon proxy

[woodser]

wallet2 already provides getters for connection information, like the daemon address and login credentials.

This PR just adds a getter for the daemon proxy URI, so it can be collected by clients too.

[nahuhh]

Those other items (login info, address) are things that the caller already knows. The proxy is not.

i'm not sure its a good idea to expose the proxy to users, unless its only available to the unrestricted rpc

edit.. this is for the wallet, so nvm.
edit again: is this for the daemon proxy, or the wallet proxy?

[woodser]

is this for the daemon proxy, or the wallet proxy?

@nahuhh

This is the wallet's proxy to its daemon.

Without this, it's not possible for a client to collect the wallet's full daemon connection information after it's set.

This accessor is merely consistent with the other available accessors, to get the wallet daemon's address and login info, allowing a client to query this information as needed.

An example use case (already used in Haveno here), is that listeners can know if the global daemon connection has changed from each wallet's daemon connection, including the proxy configuration, in order to update each wallet's daemon connection accordingly.

Without this, each wallet would have to cache and maintain this information locally. It makes sense instead that there is a consistent accessor.