consensus/ethash: move remote agent logic to ethash internal (#15853)

* consensus/ethash: start remote ggoroutine to handle remote mining

* consensus/ethash: expose remote miner api

* consensus/ethash: expose submitHashrate api

* miner, ethash: push empty block to sealer without waiting execution

* consensus, internal: add getHashrate API for ethash

* consensus: add three method for consensus interface

* miner: expose consensus engine running status to miner

* eth, miner: specify etherbase when miner created

* miner: commit new work when consensus engine is started

* consensus, miner: fix some logics

* all: delete useless interfaces

* consensus: polish a bit

internal/web3ext/web3ext.go

@@ -21,6 +21,7 @@ var Modules = map[string]string{
 	"admin":      Admin_JS,
 	"chequebook": Chequebook_JS,
 	"clique":     Clique_JS,
+	"ethash":     Ethash_JS,
 	"debug":      Debug_JS,
 	"eth":        Eth_JS,
 	"miner":      Miner_JS,
@@ -109,6 +110,34 @@ web3._extend({
 });
 `
 
+const Ethash_JS = `
+web3._extend({
+	property: 'ethash',
+	methods: [
+		new web3._extend.Method({
+			name: 'getWork',
+			call: 'ethash_getWork',
+			params: 0
+		}),
+		new web3._extend.Method({
+			name: 'getHashrate',
+			call: 'ethash_getHashrate',
+			params: 0
+		}),
+		new web3._extend.Method({
+			name: 'submitWork',
+			call: 'ethash_submitWork',
+			params: 3,
+		}),
+		new web3._extend.Method({
+			name: 'submitHashRate',
+			call: 'ethash_submitHashRate',
+			params: 2,
+		}),
+	]
+});
+`
+
 const Admin_JS = `
 web3._extend({
 	property: 'admin',