grpc: add eth_call query command (#236)

* add eth_call query command

Implement EthCall grpc query api

Closes #229

add eth_call query command

fix codec issue

use query client

use grpc status error and codes

validate address length in grpc handler

* Update x/evm/types/callargs.go

Co-authored-by: Federico Kunze Küllmer <31522760+fedekunze@users.noreply.github.com>

proto/ethermint/evm/v1alpha1/query.proto

@@ -5,6 +5,7 @@ import "gogoproto/gogo.proto";
 import "cosmos/base/query/v1beta1/pagination.proto";
 import "google/api/annotations.proto";
 import "ethermint/evm/v1alpha1/evm.proto";
+import "ethermint/evm/v1alpha1/tx.proto";
 
 option go_package = "github.com/tharsis/ethermint/x/evm/types";
 
@@ -70,6 +71,11 @@ service Query {
   rpc StaticCall(QueryStaticCallRequest) returns (QueryStaticCallResponse) {
     option (google.api.http).get = "/ethermint/evm/v1alpha1/static_call";
   }
+
+  // EthCall implements the `eth_call` rpc api
+  rpc EthCall(EthCallRequest) returns (MsgEthereumTxResponse) {
+    option (google.api.http).get = "/ethermint/evm/v1alpha1/eth_call";
+  }
 }
 
 // QueryAccountRequest is the request type for the Query/Account RPC method.
@@ -250,7 +256,13 @@ message QueryStaticCallRequest {
   bytes input = 2;
 }
 
-// // QueryStaticCallRequest defines static call response
+// QueryStaticCallRequest defines static call response
 message QueryStaticCallResponse {
   bytes data = 1;
 }
+
+// EthCallRequest defines EthCall request
+message EthCallRequest {
+  // same json format as the json rpc api.
+  bytes args = 1;
+}