Removed old rules from eslint

Tried hand at testing by fixing the spec files with import. However, still many errors and given up now.

overlord/src/app/core/account.service.spec.ts

@@ -1,10 +1,12 @@
 import { inject, TestBed } from '@angular/core/testing';
+import { HttpClientModule } from '@angular/common/http';
 
 import { AccountService } from './account.service';
 
 describe('AccountService', () => {
   beforeEach(() => {
     TestBed.configureTestingModule({
+      imports: [HttpClientModule],
       providers: [AccountService],
     });
   });

overlord/src/app/core/voucher.service.spec.ts

@@ -1,10 +1,12 @@
 import { inject, TestBed } from '@angular/core/testing';
+import { HttpClientModule } from '@angular/common/http';
 
 import { VoucherService } from './voucher.service';
 
 describe('VoucherService', () => {
   beforeEach(() => {
     TestBed.configureTestingModule({
+      imports: [HttpClientModule],
       providers: [VoucherService],
     });
   });