Add ContentRatingHelper to generate ID for content ratings

This commit introduces a new `ContentRatingHelper` class that provides functionality for setting an ID for a content rating of an app. Thus, a content rating in any language will have a unique identifier in English.

For example, a content rating having a `title` "Accord parental" or "Parental guidance" both are treated as the same content rating, with the `id` as "Parental guidance".

The `MainActivityViewModel` class has also been updated to change the resource path for loading properties.

The library version has been updated.