Refactor code to comply with ESLint rules

Major refactoring using ESLint with rules from AirBnb and Vue.

Enable most of the ESLint rules and do necessary linting in the code.
Also add more information for rules that are disabled to describe what
they are and why they are disabled.

Allow logging (`console.log`) in test files, and in development mode
(e.g. when working with `npm run serve`), but disable it when
environment is production (as pre-configured by Vue). Also add flag
(`--mode production`) in `lint:eslint` command so production linting is
executed earlier in lifecycle.

Disable rules that requires a separate work. Such as ESLint rules that
are broken in TypeScript: no-useless-constructor (eslint/eslint#14118)
and no-shadow (eslint/eslint#13014).

vue.config.js

@@ -1,66 +1,69 @@
+const { resolve } = require('path');
 const { defineConfig } = require('@vue/cli-service');
+const packageJson = require('./package.json');
 
 loadVueAppRuntimeVariables();
 
 module.exports = defineConfig({
-    chainWebpack: (config) => {
-        changeAppEntryPoint('./src/presentation/main.ts', config);
+  chainWebpack: (config) => {
+    changeAppEntryPoint('./src/presentation/main.ts', config);
+  },
+  configureWebpack: {
+    resolve: {
+      alias: { // also requires path alias in tsconfig.json
+        '@tests': resolve(__dirname, 'tests/'),
+      },
+      fallback: {
+        /* Tell webpack to ignore polyfilling them because Node core modules are never used
+            for browser code but only for desktop where Electron supports them. */
+        ...ignorePolyfills('os', 'child_process', 'fs', 'path'),
+      },
     },
-    configureWebpack:{
-        resolve: {
-            alias: {  // also requires path alias in tsconfig.json
-              "@tests": require('path').resolve(__dirname, 'tests/'),
-            },
-            fallback: {
-                /* Tell webpack to ignore polyfilling them because Node core modules are never used
-                    for browser code but only for desktop where Electron supports them. */
-                ...ignorePolyfills('os', 'child_process', 'fs', 'path'),
-            }
+    // Fix compilation failing on macOS when running unit/integration tests
+    externals: ['fsevents'],
+  },
+  pluginOptions: {
+    // https://nklayman.github.io/vue-cli-plugin-electron-builder/guide/guide.html#native-modules
+    electronBuilder: {
+      mainProcessFile: './src/presentation/electron/main.ts', // https://nklayman.github.io/vue-cli-plugin-electron-builder/guide/configuration.html#webpack-configuration
+      nodeIntegration: true, // required to reach Node.js APIs for environment specific logic
+      // https://www.electron.build/configuration/configuration
+      builderOptions: {
+        publish: [{
+          // https://www.electron.build/configuration/publish#githuboptions
+          // https://nklayman.github.io/vue-cli-plugin-electron-builder/guide/recipes.html#enable-publishing-to-github
+          provider: 'github',
+          vPrefixedTagName: false, // default: true
+          releaseType: 'release', // or "draft" (default), "prerelease"
+        }],
+        mac: { // https://www.electron.build/configuration/mac
+          target: 'dmg',
         },
-        // Fix compilation failing on macOS when running unit/integration tests
-        externals: ['fsevents'],
-    },
-    pluginOptions: {
-        // https://nklayman.github.io/vue-cli-plugin-electron-builder/guide/guide.html#native-modules
-        electronBuilder: {
-            mainProcessFile: './src/presentation/electron/main.ts', // https://nklayman.github.io/vue-cli-plugin-electron-builder/guide/configuration.html#webpack-configuration
-            nodeIntegration: true, // required to reach Node.js APIs for environment specific logic
-            // https://www.electron.build/configuration/configuration
-            builderOptions: {
-                publish: [{
-                    // https://www.electron.build/configuration/publish#githuboptions
-                    // https://nklayman.github.io/vue-cli-plugin-electron-builder/guide/recipes.html#enable-publishing-to-github
-                    provider: 'github',
-                    vPrefixedTagName: false, // default: true
-                    releaseType: 'release' // or "draft" (default), "prerelease"
-                }],
-                mac: { // https://www.electron.build/configuration/mac
-                    target: 'dmg',
-                },
-                win: { // https://www.electron.build/configuration/win
-                    target: 'nsis',
-                },
-                linux: { // https://www.electron.build/configuration/linux
-                    target: 'AppImage',
-                }
-            },
+        win: { // https://www.electron.build/configuration/win
+          target: 'nsis',
         },
+        linux: { // https://www.electron.build/configuration/linux
+          target: 'AppImage',
+        },
+      },
     },
+  },
 });
 
 function changeAppEntryPoint(entryPath, config) {
-    config.entry('app').clear().add(entryPath).end();
+  config.entry('app').clear().add(entryPath).end();
 }
 
 function loadVueAppRuntimeVariables() {
-    const packageJson = require('./package.json');
-    process.env.VUE_APP_VERSION         = packageJson.version;
-    process.env.VUE_APP_NAME            = packageJson.name;
-    process.env.VUE_APP_REPOSITORY_URL  = packageJson.repository.url;
-    process.env.VUE_APP_HOMEPAGE_URL    = packageJson.homepage;
-};
+  process.env.VUE_APP_VERSION = packageJson.version;
+  process.env.VUE_APP_NAME = packageJson.name;
+  process.env.VUE_APP_REPOSITORY_URL = packageJson.repository.url;
+  process.env.VUE_APP_HOMEPAGE_URL = packageJson.homepage;
+}
 
 function ignorePolyfills(...moduleNames) {
-    return moduleNames
-        .reduce((obj, module) => { obj[module] = false; return obj; }, {});
+  return moduleNames.reduce((obj, module) => {
+    obj[module] = false;
+    return obj;
+  }, {});
 }