Add gRPC interface to CLI settings

rpc/settings/settings.proto

@@ -0,0 +1,41 @@
+// This file is part of arduino-cli.
+//
+// Copyright 2019 ARDUINO SA (http://www.arduino.cc/)
+//
+// This software is released under the GNU General Public License version 3,
+// which covers the main part of arduino-cli.
+// The terms of this license can be found at:
+// https://www.gnu.org/licenses/gpl-3.0.en.html
+//
+// You can be released from the requirements of the above licenses by purchasing
+// a commercial license. Buying such a license is mandatory if you want to
+// modify or otherwise use the software for commercial activities involving the
+// Arduino software without disclosing the source code of your own applications.
+// To purchase a commercial license, send an email to license@arduino.cc.
+
+syntax = "proto3";
+
+package cc.arduino.cli.settings;
+
+option go_package = "github.com/arduino/arduino-cli/rpc/settings";
+
+service Settings {
+  rpc GetAll(GetAllRequest) returns (AllSettings);
+  rpc SetAll(AllSettings) returns (SetAllResponse);
+  rpc GetValue(GetValueRequest) returns (Value);
+  rpc SetValue(Value) returns (SetValueResponse);
+}
+
+message AllSettings {
+    string jsonData = 1;
+}
+
+message Value {
+  string key = 1;
+  string jsonData = 2;
+}
+
+message GetAllRequest {}
+message GetValueRequest { string key = 1; }
+message SetAllResponse {}
+message SetValueResponse {}