feat: gRPC mempool service (#275)

* make file nit

* base app set up

* make file update

* makefile nit

* adding service test to e2e

* lint

* type fix

* nit

* unit test + readme

testutils/utils.go

@@ -2,7 +2,11 @@ package testutils
 
 import (
 	"math/rand"
+	"testing"
 
+	"cosmossdk.io/log"
+	"cosmossdk.io/math"
+	storetypes "cosmossdk.io/store/types"
 	txsigning "cosmossdk.io/x/tx/signing"
 	"github.com/cosmos/cosmos-sdk/client"
 	"github.com/cosmos/cosmos-sdk/codec"
@@ -12,6 +16,7 @@ import (
 	"github.com/cosmos/cosmos-sdk/crypto/keys/ed25519"
 	"github.com/cosmos/cosmos-sdk/crypto/keys/secp256k1"
 	cryptotypes "github.com/cosmos/cosmos-sdk/crypto/types"
+	"github.com/cosmos/cosmos-sdk/testutil"
 	sdk "github.com/cosmos/cosmos-sdk/types"
 	"github.com/cosmos/cosmos-sdk/types/tx/signing"
 	authsigning "github.com/cosmos/cosmos-sdk/x/auth/signing"
@@ -20,6 +25,13 @@ import (
 	stakingtypes "github.com/cosmos/cosmos-sdk/x/staking/types"
 	"github.com/cosmos/gogoproto/proto"
 
+	signerextraction "github.com/skip-mev/block-sdk/adapters/signer_extraction_adapter"
+	"github.com/skip-mev/block-sdk/block"
+	"github.com/skip-mev/block-sdk/block/base"
+	"github.com/skip-mev/block-sdk/block/mocks"
+	defaultlane "github.com/skip-mev/block-sdk/lanes/base"
+	"github.com/skip-mev/block-sdk/lanes/free"
+	"github.com/skip-mev/block-sdk/lanes/mev"
 	auctiontypes "github.com/skip-mev/block-sdk/x/auction/types"
 )
 
@@ -30,6 +42,66 @@ type EncodingConfig struct {
 	Amino             *codec.LegacyAmino
 }
 
+// CreateBaseSDKContext creates a base sdk context with the default store key and transient key.
+func CreateBaseSDKContext(t *testing.T) sdk.Context {
+	key := storetypes.NewKVStoreKey(auctiontypes.StoreKey)
+
+	testCtx := testutil.DefaultContextWithDB(
+		t,
+		key,
+		storetypes.NewTransientStoreKey("transient_test"),
+	)
+
+	return testCtx.Ctx
+}
+
+func CreateMempool() *block.LanedMempool {
+	encodingConfig := CreateTestEncodingConfig()
+	signerExtractor := signerextraction.NewDefaultAdapter()
+
+	mevConfig := base.LaneConfig{
+		SignerExtractor: signerExtractor,
+		Logger:          log.NewNopLogger(),
+		TxEncoder:       encodingConfig.TxConfig.TxEncoder(),
+		TxDecoder:       encodingConfig.TxConfig.TxDecoder(),
+		AnteHandler:     nil,
+		MaxBlockSpace:   math.LegacyZeroDec(),
+		MaxTxs:          0, // unlimited
+	}
+	factory := mev.NewDefaultAuctionFactory(encodingConfig.TxConfig.TxDecoder(), signerExtractor)
+	mevLane := mev.NewMEVLane(mevConfig, factory, factory.MatchHandler())
+
+	freeConfig := base.LaneConfig{
+		SignerExtractor: signerExtractor,
+		Logger:          log.NewNopLogger(),
+		TxEncoder:       encodingConfig.TxConfig.TxEncoder(),
+		TxDecoder:       encodingConfig.TxConfig.TxDecoder(),
+		AnteHandler:     nil,
+		MaxBlockSpace:   math.LegacyZeroDec(),
+		MaxTxs:          0, // unlimited
+	}
+	freeLane := free.NewFreeLane[string](freeConfig, base.DefaultTxPriority(), free.DefaultMatchHandler())
+
+	defaultConfig := base.LaneConfig{
+		SignerExtractor: signerExtractor,
+		Logger:          log.NewNopLogger(),
+		TxEncoder:       encodingConfig.TxConfig.TxEncoder(),
+		TxDecoder:       encodingConfig.TxConfig.TxDecoder(),
+		AnteHandler:     nil,
+		MaxBlockSpace:   math.LegacyZeroDec(),
+		MaxTxs:          0, // unlimited
+	}
+	defaultLane := defaultlane.NewDefaultLane(defaultConfig, base.DefaultMatchHandler())
+
+	lanes := []block.Lane{mevLane, freeLane, defaultLane}
+	mempool, err := block.NewLanedMempool(log.NewNopLogger(), lanes, mocks.MockLaneFetcher{})
+	if err != nil {
+		panic(err)
+	}
+
+	return mempool
+}
+
 func CreateTestEncodingConfig() EncodingConfig {
 	interfaceRegistry, err := types.NewInterfaceRegistryWithOptions(types.InterfaceRegistryOptions{
 		ProtoFiles: proto.HybridResolver,