Proposal: Integrate Sponsor Mechanism for Transaction Fees about gno HOT 2 OPEN

var msgs = []std.Msg{
     vm.MsgCall{
         Caller:  sponsorInfo.Address,
         // PkgPath: "gno.land/r/demo/counter",
         // Func:    "Increase",
         // Args:    nil,
         // Send:    std.MustParseCoins("1000000ugnot"),
     },
     vm.MsgCall{
         Caller:  senderInfo.Address,
         PkgPath: "gno.land/r/demo/counter",
         Func:    "Increase",
         Args:    nil,
         // Send:    std.MustParseCoins("1000000ugnot"),
     },
 }

   tx.Signatures = append(tx.Signatures,
       std.Signature{
           PubKey:    sponsorPubKey,
           Signature: sponsorSignature,
       },
       std.Signature{
           PubKey:    senderPubKey,
           Signature: senderSignature,
       },
   )

func (msg MsgCall) ValidateBasic() error {
   if msg.Caller.IsZero() {
       return std.ErrInvalidAddress("missing caller address")
   }
   if msg.PkgPath == "" { // XXX
       return ErrInvalidPkgPath("missing package path")
   }
   if msg.Func == "" { // XXX
       return ErrInvalidExpr("missing function to call")
   }
   return nil
}

{
  "jsonrpc": "2.0",
  "id": "",
  "result": {
    "height": "543",
    "results": {
      "deliver_tx": [
        {
          "ResponseBase": {
            "Error": null,
            "Data": "CgooMjAgdWludDY0KQoK",
            "Events": [
              {
                "@type": "/tm.gnoEvent",
                "type": "g1y490harzjqmdngmmaw4tyc4qdm5ma5k0fv3w6p : 20",
                "pkg_path": "gno.land/r/demo/counter",
                "func": "Increase",
                "attrs": null
              },
              {
                "@type": "/tm.gnoEvent",
                "type": "g1y490harzjqmdngmmaw4tyc4qdm5ma5k0fv3w6p : 20",
                "pkg_path": "gno.land/r/demo/counter",
                "func": "Increase",
                "attrs": null
              }
            ],
            "Log": "msg:0,success:true,log:,events:[]\nmsg:1,success:true,log:,events:[]",
            "Info": ""
          },
          "GasWanted": "1000000",
          "GasUsed": "274145"
        }
      ],
      "end_block": {
        "ResponseBase": {
          "Error": null,
          "Data": null,
          "Events": null,
          "Log": "",
          "Info": ""
        },
        "ValidatorUpdates": null,
        "ConsensusParams": null,
        "Events": null
      },
      "begin_block": {
        "ResponseBase": {
          "Error": null,
          "Data": null,
          "Events": null,
          "Log": "",
          "Info": ""
        }
      }
    }
  }
}