Add types and methods for participants onboarding module (#12)

Part of [laconicd testnet validator enrollment](https://www.notion.so/laconicd-testnet-validator-enrollment-6fc1d3cafcc64fef8c5ed3affa27c675)

Co-authored-by: Isha Venikar <145848618+IshaVenikar@users.noreply.github.com>
Co-authored-by: Prathamesh Musale <prathamesh.musale0@gmail.com>
Reviewed-on: cerc-io/registry-sdk#12
Co-authored-by: Nabarun <nabarun@deepstacksoft.com>
Co-committed-by: Nabarun <nabarun@deepstacksoft.com>

proto/cerc/onboarding/module/v1/module.proto

@@ -0,0 +1,15 @@
+syntax = "proto3";
+
+package cerc.onboarding.module.v1;
+
+import "cosmos/app/v1alpha1/module.proto";
+
+// Module is the app config object of the module.
+// Learn more: https://docs.cosmos.network/main/building-modules/depinject
+message Module {
+  option (cosmos.app.v1alpha1.module) = {
+    go_import : "git.vdb.to/cerc-io/laconicd/x/onboarding"
+  };
+
+  string authority = 1;
+}

proto/cerc/onboarding/v1/genesis.proto

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+syntax = "proto3";
+
+package cerc.onboarding.v1;
+
+import "gogoproto/gogo.proto";
+import "cerc/onboarding/v1/onboarding.proto";
+
+option go_package = "git.vdb.to/cerc-io/laconicd/x/onboarding";
+
+// GenesisState defines the onboarding module's genesis state.
+message GenesisState {
+  // params defines all the parameters of the module.
+  Params params = 1 [ (gogoproto.nullable) = false ];
+  // participants defines all the participants
+  repeated Participant participants = 2 [ (gogoproto.nullable) = false ];
+}

proto/cerc/onboarding/v1/onboarding.proto

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+syntax = "proto3";
+
+package cerc.onboarding.v1;
+
+import "gogoproto/gogo.proto";
+
+option go_package = "git.vdb.to/cerc-io/laconicd/x/onboarding";
+
+// Params defines the parameters of the onboarding module.
+message Params {
+  bool onboarding_enabled = 1 [
+    (gogoproto.moretags) = "json:\"onboarding_enabled\" yaml:\"onboarding_enabled\""
+  ];
+}
+
+// Participant defines the data that will be stored for each enrolled participant
+message Participant {
+  string cosmos_address = 1 [
+    (gogoproto.moretags) = "json:\"cosmos_address\" yaml:\"cosmos_address\""
+  ];
+
+  string nitro_address = 2 [
+    (gogoproto.moretags) = "json:\"nitro_address\" yaml:\"nitro_address\""
+  ];
+}
+// EthPayload defines the payload that is signed by the ethereum private key
+message EthPayload {
+  string address = 1 [
+    (gogoproto.moretags) = "json:\"address\" yaml:\"address\""
+  ];
+
+  string msg = 2 [
+    (gogoproto.moretags) = "json:\"msg\" yaml:\"msg\""
+  ];
+}

proto/cerc/onboarding/v1/query.proto

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+syntax = "proto3";
+
+package cerc.onboarding.v1;
+
+import "gogoproto/gogo.proto";
+import "cosmos/base/query/v1beta1/pagination.proto";
+import "cerc/onboarding/v1/onboarding.proto";
+import "google/api/annotations.proto";
+
+option go_package = "git.vdb.to/cerc-io/laconicd/x/onboarding";
+
+// Query defines the gRPC querier service for onboarding module
+service Query {
+  // Participants queries Participants list
+  rpc Participants(QueryParticipantsRequest) returns (QueryParticipantsResponse) {
+    option (google.api.http).get = "/cerc/onboarding/v1/participants";
+  }
+}
+
+// QueryParticipantsRequest queries participants
+message QueryParticipantsRequest {
+  // pagination defines an optional pagination for the request.
+  cosmos.base.query.v1beta1.PageRequest pagination = 1;
+}
+
+// QueryParticipantsResponse is response type for get the participants
+message QueryParticipantsResponse {
+  repeated Participant participants = 1
+      [ (gogoproto.moretags) = "json:\"participants\" yaml:\"participants\"" ];
+
+  // pagination defines the pagination in the response.
+  cosmos.base.query.v1beta1.PageResponse pagination = 2;
+}

proto/cerc/onboarding/v1/tx.proto

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+syntax = "proto3";
+
+package cerc.onboarding.v1;
+
+import "cosmos/msg/v1/msg.proto";
+import "google/api/annotations.proto";
+import "gogoproto/gogo.proto";
+import "cerc/onboarding/v1/onboarding.proto";
+
+option go_package = "git.vdb.to/cerc-io/laconicd/x/onboarding";
+
+// Msg defines the onboarding Msg service.
+service Msg {
+  option (cosmos.msg.v1.service) = true;
+
+  // OnboardParticipant defines a method for enrolling a new validator.
+  rpc OnboardParticipant(MsgOnboardParticipant)
+    returns (MsgOnboardParticipantResponse) {
+      option (google.api.http).post = "/cerc/onboarding/v1/onboard_participant";
+    };
+}
+
+// MsgOnboardParticipant defines a SDK message for enrolling a new validator.
+message MsgOnboardParticipant {
+  option (cosmos.msg.v1.signer) = "participant";
+
+  // Participant is the msg sender
+  string participant = 1;
+  EthPayload eth_payload = 2 [ (gogoproto.nullable) = false ];
+  string eth_signature = 3;
+}
+
+// MsgOnboardParticipantResponse defines the Msg/OnboardParticipant response type.
+message MsgOnboardParticipantResponse {}