node: refactor package node (#21105)

This PR significantly changes the APIs for instantiating Ethereum nodes in
a Go program. The new APIs are not backwards-compatible, but we feel that
this is made up for by the much simpler way of registering services on
node.Node. You can find more information and rationale in the design
document: https://gist.github.com/renaynay/5bec2de19fde66f4d04c535fd24f0775.

There is also a new feature in Node's Go API: it is now possible to
register arbitrary handlers on the user-facing HTTP server. In geth, this
facility is used to enable GraphQL.

There is a single minor change relevant for geth users in this PR: The
GraphQL API is no longer available separately from the JSON-RPC HTTP
server. If you want GraphQL, you need to enable it using the
./geth --http --graphql flag combination.

The --graphql.port and --graphql.addr flags are no longer available.

cmd/geth/usage.go

@@ -142,8 +142,6 @@ var AppHelpFlagGroups = []flags.FlagGroup{
 			utils.WSApiFlag,
 			utils.WSAllowedOriginsFlag,
 			utils.GraphQLEnabledFlag,
-			utils.GraphQLListenAddrFlag,
-			utils.GraphQLPortFlag,
 			utils.GraphQLCORSDomainFlag,
 			utils.GraphQLVirtualHostsFlag,
 			utils.RPCGlobalGasCap,
@@ -231,6 +229,8 @@ var AppHelpFlagGroups = []flags.FlagGroup{
 			utils.LegacyWSApiFlag,
 			utils.LegacyGpoBlocksFlag,
 			utils.LegacyGpoPercentileFlag,
+			utils.LegacyGraphQLListenAddrFlag,
+			utils.LegacyGraphQLPortFlag,
 		}, debug.DeprecatedFlags...),
 	},
 	{