cmd, ethdb, vendor: integrate leveldb iostats (#16277)

* cmd, dashboard, ethdb, vendor: send iostats to dashboard

* ethdb: change names

* ethdb: handle parsing errors

* ethdb: handle iostats syntax error

* ethdb: r -> w

vendor/github.com/syndtr/goleveldb/leveldb/util/util.go

@@ -19,7 +19,7 @@ var (
 // Releaser is the interface that wraps the basic Release method.
 type Releaser interface {
 	// Release releases associated resources. Release should always success
-	// and can be called multipe times without causing error.
+	// and can be called multiple times without causing error.
 	Release()
 }