feat: EmptyAppOptions implement DynamicConfig (backport #23440) (#23446)

Co-authored-by: Julien Robert <julien@rbrt.fr>
Co-authored-by: aljo242 <alex@interchainlabs.io>

testutil/sims/app_helpers.go

@@ -10,6 +10,7 @@ import (
 	cmtjson "github.com/cometbft/cometbft/libs/json"
 	cmttypes "github.com/cometbft/cometbft/types"
 
+	"cosmossdk.io/core/server"
 	corestore "cosmossdk.io/core/store"
 	coretesting "cosmossdk.io/core/testing"
 	"cosmossdk.io/depinject"
@@ -282,6 +283,8 @@ func GenesisStateWithValSet(
 	return genesisState, nil
 }
 
+var _ server.DynamicConfig = EmptyAppOptions{}
+
 // EmptyAppOptions is a stub implementing AppOptions
 type EmptyAppOptions struct{}
 
@@ -290,6 +293,11 @@ func (ao EmptyAppOptions) Get(o string) interface{} {
 	return nil
 }
 
+// GetString implements AppOptions
+func (ao EmptyAppOptions) GetString(o string) string {
+	return ""
+}
+
 // AppOptionsMap is a stub implementing AppOptions which can get data from a map
 type AppOptionsMap map[string]interface{}