Re-define sub mining routes properly and use router outlet

frontend/src/app/components/mining-start/mining-start.component.html

@@ -0,0 +1 @@
+<router-outlet></router-outlet>

frontend/src/app/components/mining-start/mining-start.component.ts

@@ -0,0 +1,14 @@
+import { Component, OnInit } from '@angular/core';
+
+@Component({
+  selector: 'app-mining-start',
+  templateUrl: './mining-start.component.html',
+})
+export class MiningStartComponent implements OnInit {
+
+  constructor() { }
+
+  ngOnInit(): void {
+  }
+
+}