cmd/geth: graceful shutdown if disk is full (#22103)

Adding warnings of free disk space left and graceful shutdown when there is not enough space left.
This also adds a flag datadir.minfreedisk which can be used to set the trigger for low disk space, and setting it to zero disables the check. 

Co-authored-by: Martin Holst Swende <martin@swende.se>
Co-authored-by: Felix Lange <fjl@twurst.com>

cmd/geth/main.go

@@ -65,6 +65,7 @@ var (
 		utils.LegacyBootnodesV5Flag,
 		utils.DataDirFlag,
 		utils.AncientFlag,
+		utils.MinFreeDiskSpaceFlag,
 		utils.KeyStoreDirFlag,
 		utils.ExternalSignerFlag,
 		utils.NoUSBFlag,
@@ -368,7 +369,7 @@ func startNode(ctx *cli.Context, stack *node.Node, backend ethapi.Backend) {
 	debug.Memsize.Add("node", stack)
 
 	// Start up the node itself
-	utils.StartNode(stack)
+	utils.StartNode(ctx, stack)
 
 	// Unlock any account specifically requested
 	unlockAccounts(ctx, stack)