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).

src/domain/ScriptingDefinition.ts

@@ -2,31 +2,32 @@ import { ScriptingLanguage } from './ScriptingLanguage';
 import { IScriptingDefinition } from './IScriptingDefinition';
 
 export class ScriptingDefinition implements IScriptingDefinition {
-    public readonly fileExtension: string;
-    constructor(
-            public readonly language: ScriptingLanguage,
-            public readonly startCode: string,
-            public readonly endCode: string,
-        ) {
-        this.fileExtension = findExtension(language);
-        validateCode(startCode, 'start code');
-        validateCode(endCode, 'end code');
-    }
+  public readonly fileExtension: string;
+
+  constructor(
+    public readonly language: ScriptingLanguage,
+    public readonly startCode: string,
+    public readonly endCode: string,
+  ) {
+    this.fileExtension = findExtension(language);
+    validateCode(startCode, 'start code');
+    validateCode(endCode, 'end code');
+  }
 }
 
 function findExtension(language: ScriptingLanguage): string {
-    switch (language) {
-        case ScriptingLanguage.shellscript:
-            return 'sh';
-        case ScriptingLanguage.batchfile:
-            return 'bat';
-        default:
-            throw new Error(`unsupported language: ${language}`);
-    }
+  switch (language) {
+    case ScriptingLanguage.shellscript:
+      return 'sh';
+    case ScriptingLanguage.batchfile:
+      return 'bat';
+    default:
+      throw new Error(`unsupported language: ${language}`);
+  }
 }
 
 function validateCode(code: string, name: string) {
-    if (!code) {
-        throw new Error(`undefined ${name}`);
-    }
+  if (!code) {
+    throw new Error(`undefined ${name}`);
+  }
 }