state-diff configs & kv functions (#15903)

* state-diff configs

* state diff kv functions

* potuz's comments

* Update config.go

* fix merge conflicts

* apply bazel's suggestion and fix some bugs

* preston's feedback

config/features/config.go

@@ -51,6 +51,8 @@ type Flags struct {
 	EnableExperimentalAttestationPool   bool // EnableExperimentalAttestationPool enables an experimental attestation pool design.
 	DisableDutiesV2                     bool // DisableDutiesV2 sets validator client to use the get Duties endpoint
 	EnableWeb                           bool // EnableWeb enables the webui on the validator client
+	EnableStateDiff                     bool // EnableStateDiff enables the experimental state diff feature for the beacon node.
+
 	// Logging related toggles.
 	DisableGRPCConnectionLogs bool // Disables logging when a new grpc client has connected.
 	EnableFullSSZDataLogging  bool // Enables logging for full ssz data on rejected gossip messages
@@ -284,6 +286,16 @@ func ConfigureBeaconChain(ctx *cli.Context) error {
 		cfg.DisableLastEpochTargets = true
 	}
 
+	if ctx.IsSet(enableStateDiff.Name) {
+		logEnabled(enableStateDiff)
+		cfg.EnableStateDiff = true
+
+		if ctx.IsSet(enableHistoricalSpaceRepresentation.Name) {
+			log.Warn("--enable-state-diff is enabled, ignoring --enable-historical-space-representation flag.")
+			cfg.EnableHistoricalSpaceRepresentation = false
+		}
+	}
+
 	cfg.AggregateIntervals = [3]time.Duration{aggregateFirstInterval.Value, aggregateSecondInterval.Value, aggregateThirdInterval.Value}
 	Init(cfg)
 	return nil

config/features/flags.go

@@ -172,6 +172,10 @@ var (
 		Name:  "enable-experimental-attestation-pool",
 		Usage: "Enables an experimental attestation pool design.",
 	}
+	enableStateDiff = &cli.BoolFlag{
+		Name:  "enable-state-diff",
+		Usage: "Enables the experimental state diff feature.",
+	}
 	// forceHeadFlag is a flag to force the head of the beacon chain to a specific block.
 	forceHeadFlag = &cli.StringFlag{
 		Name: "sync-from",