Improve script/category name validation

- Use better error messages with more context.
- Unify their validation logic and share tests.
- Validate also type of the name.
- Refactor node (Script/Category) parser tests for easier future
  changes and cleaner test code (using `TestBuilder` to do dirty work in
  unified way).
- Add more tests. Custom `Error` properties are compared manually due to
  `chai` not supporting deep equality checks (chaijs/chai#1065,
  chaijs/chai#1405).

tests/unit/shared/Stubs/EnumParserStub.ts

@@ -23,9 +23,9 @@ export class EnumParserStub<T> implements IEnumParser<T> {
     if (scenario) {
       return scenario.outputValue;
     }
-    if (this.defaultValue) {
+    if (this.defaultValue !== undefined) {
       return this.defaultValue;
     }
-    throw new Error('enum parser is not set up');
+    throw new Error(`Don't know now what to return from ${EnumParserStub.name}, forgot to set-up?`);
   }
 }