refactor(@angular-devkit/build-angular): move karma plugin in own folder

Author: alan-agius4

packages/angular_devkit/build_angular/plugins/karma.ts

@@ -6,4 +6,4 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
-module.exports = require('../src/webpack/plugins/karma');
+module.exports = require('../src/webpack/plugins/karma/karma');

packages/angular_devkit/build_angular/src/webpack/plugins/karma-context.html renamed to packages/angular_devkit/build_angular/src/webpack/plugins/karma/karma-context.html

@@ -14,12 +14,12 @@ import * as webpack from 'webpack';
 const webpackDevMiddleware = require('webpack-dev-middleware');
 
 import { KarmaWebpackFailureCb } from './karma-webpack-failure-cb';
-import { statsErrorsToString } from '../utils/stats';
-import { getWebpackStatsConfig } from '../configs/stats';
+import { statsErrorsToString } from '../../utils/stats';
+import { getWebpackStatsConfig } from '../../configs/stats';
 import { createConsoleLogger } from '@angular-devkit/core/node';
 import { logging } from '@angular-devkit/core';
-import { WebpackTestOptions } from '../../utils/build-options';
-import { normalizeSourceMaps } from '../../utils/index';
+import { WebpackTestOptions } from '../../../utils/build-options';
+import { normalizeSourceMaps } from '../../../utils/index';
 
 /**
  * Enumerate needed (but not require/imported) dependencies from this file