GlobalStateService and Reward stale APIs

[brusherru]

The implementation of a few API endpoints and the Reward message type has been changed:
spacemeshos/go-spacemesh@697adda

So this repo needs an update to represent an actual API:

• GlobalStateService.SmesherRewardStream and GlobalStateService.SmesherDataQuery are deprecated: they throws an exception "UNIMPLEMENTED DEPRECATED". So let's remove them from proto files.
• Reward type (that returned within GlobalStateService.AccountDataQuery/Stream endpoints) has no more SmesherID field

Changes not released within v0.2.16-beta.0 are out of scope.

@countvonzero am I missing something else?

[lrettig]

See also: spacemeshos/go-spacemesh#3257

[lrettig]

As discussed in the linked issue/go-spacemesh repo discussion, these changes are not urgent, but it would be good to add new endpoint(s) to stream and/or query rewards from a given smesher, since the node does have this data (but it's not persisted to the mesh, not part of the protocol, and it's ephemeral since it lives in proposals and cannot be reconstructed).