ethstats: fix URL parser for '@' or ':' in node name/password (#21640)

Fixes the case (example below) where the value passed
to --ethstats flag would be parsed wrongly because the
node name and/or password value contained the special
characters '@' or ':'

    --ethstats "ETC Labs Metrics @meowsbits":mypass@ws://mordor.dash.fault.dev:3000

ethstats/ethstats_test.go

@@ -0,0 +1,67 @@
+package ethstats
+
+import (
+	"strconv"
+	"testing"
+)
+
+func TestParseEthstatsURL(t *testing.T) {
+	cases := []struct {
+		url              string
+		node, pass, host string
+	}{
+		{
+			url:  `"debug meowsbits":mypass@ws://mordor.dash.fault.dev:3000`,
+			node: "debug meowsbits", pass: "mypass", host: "ws://mordor.dash.fault.dev:3000",
+		},
+		{
+			url:  `"debug @meowsbits":mypass@ws://mordor.dash.fault.dev:3000`,
+			node: "debug @meowsbits", pass: "mypass", host: "ws://mordor.dash.fault.dev:3000",
+		},
+		{
+			url:  `"debug: @meowsbits":mypass@ws://mordor.dash.fault.dev:3000`,
+			node: "debug: @meowsbits", pass: "mypass", host: "ws://mordor.dash.fault.dev:3000",
+		},
+		{
+			url:  `name:@ws://mordor.dash.fault.dev:3000`,
+			node: "name", pass: "", host: "ws://mordor.dash.fault.dev:3000",
+		},
+		{
+			url:  `name@ws://mordor.dash.fault.dev:3000`,
+			node: "name", pass: "", host: "ws://mordor.dash.fault.dev:3000",
+		},
+		{
+			url:  `:mypass@ws://mordor.dash.fault.dev:3000`,
+			node: "", pass: "mypass", host: "ws://mordor.dash.fault.dev:3000",
+		},
+		{
+			url:  `:@ws://mordor.dash.fault.dev:3000`,
+			node: "", pass: "", host: "ws://mordor.dash.fault.dev:3000",
+		},
+	}
+
+	for i, c := range cases {
+		parts, err := parseEthstatsURL(c.url)
+		if err != nil {
+			t.Fatal(err)
+		}
+		node, pass, host := parts[0], parts[1], parts[2]
+
+		// unquote because the value provided will be used as a CLI flag value, so unescaped quotes will be removed
+		nodeUnquote, err := strconv.Unquote(node)
+		if err == nil {
+			node = nodeUnquote
+		}
+
+		if node != c.node {
+			t.Errorf("case=%d mismatch node value, got: %v ,want: %v", i, node, c.node)
+		}
+		if pass != c.pass {
+			t.Errorf("case=%d mismatch pass value, got: %v ,want: %v", i, pass, c.pass)
+		}
+		if host != c.host {
+			t.Errorf("case=%d mismatch host value, got: %v ,want: %v", i, host, c.host)
+		}
+	}
+
+}