cmd, consensus, core, miner: instatx clique for --dev (#15323)

* cmd, consensus, core, miner: instatx clique for --dev

* cmd, consensus, clique: support configurable --dev block times

* cmd, core: allow --dev to use persistent storage too

cmd/geth/main.go

@@ -99,7 +99,8 @@ var (
 		utils.NetrestrictFlag,
 		utils.NodeKeyFileFlag,
 		utils.NodeKeyHexFlag,
-		utils.DevModeFlag,
+		utils.DeveloperFlag,
+		utils.DeveloperPeriodFlag,
 		utils.TestnetFlag,
 		utils.RinkebyFlag,
 		utils.VMEnableDebugFlag,
@@ -270,7 +271,7 @@ func startNode(ctx *cli.Context, stack *node.Node) {
 		}
 	}()
 	// Start auxiliary services if enabled
-	if ctx.GlobalBool(utils.MiningEnabledFlag.Name) {
+	if ctx.GlobalBool(utils.MiningEnabledFlag.Name) || ctx.GlobalBool(utils.DeveloperFlag.Name) {
 		// Mining only makes sense if a full Ethereum node is running
 		var ethereum *eth.Ethereum
 		if err := stack.Service(&ethereum); err != nil {