feat(core): add store API (#14227)

core/appmodule/service.go

@@ -0,0 +1,19 @@
+package appmodule
+
+import (
+	"cosmossdk.io/core/intermodule"
+	"cosmossdk.io/core/store"
+)
+
+// Service bundles all the core services provided by a compliant runtime
+// implementation into a single services.
+//
+// NOTE: If new core services are provided after core v1, they shouldn't be added to this
+// interface which would be API breaking, but rather a cosmossdk.io/core/appmodule/v2.Service
+// should be created which extends this Service interface with new services.
+type Service interface {
+	store.KVStoreService
+	store.MemoryStoreService
+	store.TransientStoreService
+	intermodule.Client
+}