refactor!: Remove clientCtx.JSONCodec and rename EncodingConfig.Marshaler to Codec (#9521)

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## Description

Closes: #9499 

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testutil/network/network.go

@@ -103,13 +103,13 @@ func DefaultConfig() Config {
 	encCfg := simapp.MakeTestEncodingConfig()
 
 	return Config{
-		Codec:             encCfg.Marshaler,
+		Codec:             encCfg.Codec,
 		TxConfig:          encCfg.TxConfig,
 		LegacyAmino:       encCfg.Amino,
 		InterfaceRegistry: encCfg.InterfaceRegistry,
 		AccountRetriever:  authtypes.AccountRetriever{},
 		AppConstructor:    NewAppConstructor(encCfg),
-		GenesisState:      simapp.ModuleBasics.DefaultGenesis(encCfg.Marshaler),
+		GenesisState:      simapp.ModuleBasics.DefaultGenesis(encCfg.Codec),
 		TimeoutCommit:     2 * time.Second,
 		ChainID:           "chain-" + tmrand.NewRand().Str(6),
 		NumValidators:     4,