cmd/geth: add flag --dev.gaslimit for dev mode (#23686)

* cmd, core: add flag --dev.gaslimit to allow configuring initial block gas limit in dev mode

* core: use provided gaslimit

Co-authored-by: Martin Holst Swende <martin@swende.se>

cmd/geth/main.go

@@ -140,6 +140,7 @@ var (
 		utils.MainnetFlag,
 		utils.DeveloperFlag,
 		utils.DeveloperPeriodFlag,
+		utils.DeveloperGasLimitFlag,
 		utils.RopstenFlag,
 		utils.SepoliaFlag,
 		utils.RinkebyFlag,

cmd/geth/usage.go

@@ -75,6 +75,7 @@ var AppHelpFlagGroups = []flags.FlagGroup{
 		Flags: []cli.Flag{
 			utils.DeveloperFlag,
 			utils.DeveloperPeriodFlag,
+			utils.DeveloperGasLimitFlag,
 		},
 	},
 	{