unified-storage: sqlkv skeleton (#115176)

* implement sqlkv skeleton and include sqlkv in badgerkv tests

pkg/setting/setting.go

@@ -618,6 +618,7 @@ type Cfg struct {
 	EnableSearch                               bool
 	OverridesFilePath                          string
 	OverridesReloadInterval                    time.Duration
+	EnableSQLKVBackend                         bool
 
 	// Secrets Management
 	SecretsManagement SecretsManagerSettings

pkg/setting/setting_unified_storage.go

@@ -100,6 +100,9 @@ func (cfg *Cfg) setUnifiedStorageConfig() {
 	cfg.OverridesFilePath = section.Key("overrides_path").String()
 	cfg.OverridesReloadInterval = section.Key("overrides_reload_period").MustDuration(30 * time.Second)
 
+	// use sqlkv (resource/sqlkv) instead of the sql backend (sql/backend) as the StorageServer
+	cfg.EnableSQLKVBackend = section.Key("enable_sqlkv_backend").MustBool(false)
+
 	cfg.MaxFileIndexAge = section.Key("max_file_index_age").MustDuration(0)
 	cfg.MinFileIndexBuildVersion = section.Key("min_file_index_build_version").MustString("")
 }