remote_id: Added arm status stream

protos/remote_id/remote_id.proto

@@ -32,6 +32,10 @@ service RemoteIdService {
      * Update the SetSelfId structure sent with the self_id packet
      */
     rpc SetSelfId(SetSelfIdRequest) returns(SetSelfIdResponse) { option (mavsdk.options.async_type) = SYNC; }
+    /*
+     * Subscribe to arm status updates.
+     */
+    rpc SubscribeArmStatus(SubscribeArmStatusRequest) returns(stream ArmStatusResponse) {}
 }
 
 message SetBasicIdRequest {
@@ -76,6 +80,11 @@ message SetSelfIdResponse {
     RemoteIdResult remote_id_result = 1;
 }
 
+message SubscribeArmStatusRequest { }
+message ArmStatusResponse {
+    ArmStatus arm_status = 1;
+}
+
 message BasicId {
     enum IdType {
         ID_TYPE_NONE = 0; // No type defined.
@@ -261,6 +270,16 @@ message SelfId {
     string description = 2; // Text description or numeric value expressed as ASCII characters.
 }
 
+message ArmStatus {
+    enum Status {
+        STATUS_GOOD_TO_ARM = 0; // Passing arming checks.
+        STATUS_PRE_ARM_FAIL_GENERIC = 1; // Generic arming failure, see error string for details.
+    }
+
+    Status status = 1; // Status level indicating if arming is allowed.
+    string error = 2;  // Text error message, should be empty if status is good to arm. Fill with nulls in unused portion.
+}
+
 // Result type.
 message RemoteIdResult {
     // Possible results returned for camera commands