cmd/utils, node: remove unused solc references and improve RPC config (#14324)

Currently http cors and websocket origins are a comma separated string in the
config object. These are replaced with string arrays that are more expressive in
case of a config file.

cmd/geth/usage.go

@@ -174,12 +174,6 @@ var AppHelpFlagGroups = []flagGroup{
 			utils.WhisperEnabledFlag,
 		},
 	},
-	{
-		Name: "MISCELLANEOUS",
-		Flags: []cli.Flag{
-			utils.SolcPathFlag,
-		},
-	},
 }
 
 func init() {