In this commit, we add a full implementation of the new SignerServer sub
RPC service within the main root RPC service. This service is able to
fully manage its macaroons, and service any connected clients. Atm, this
service only has a single method: SignOutputRaw which mimics the
existing lnwallet.Signer interface within lnd itself. As the API's are
so similar, it will be possible for a client to directly use the
lnwallet.Signer interface, and have a proxy that sends the request over
RPC, and translates the proto layer on both sides. To the client, it
doesn't know that it's using a remote, or local RPC.
In this commit, we add a new proto generation script to match the one in
the main lnrpc package. This script differs, as we don't need to
generate the REST proxy stuff (for now).
In this commit, we introduce a new sub-package within the greater RPC
package. This new sub-package will house a new set of sub-RPC servers
to expose experimental features behind build flags for upstream
consumers. In this commit, we add the first config for the service,
which will simply expose the lnwallet.Signer interface over RPC.
In the default file, we have what the config will be if the build tag
(signerrpc) is off. In this case, the config parser won't detect any
times, and if specified will error out. In the active file, we have the
true config that the server will use. With this new set up, we'll
exploit these build flags heavily in order to create a generalized
framework for adding additional sub RPC servers.
