Chapters: Use the Chapter Number as chapterId

[Seyden]

• Removed the use of using the slug as the chapterId
• Save the link of the chapter for each chapter into the StateManager
• If getChapterDetails is called, it will first check if the chapterlink was already saved to the StateManager, if not it will call getChapters and request all chapterLinks for the manga and save them

This change is intended to prevent old data being used and using old slugs as the chapterId

[TheNetsky]

After discussion, this is going to excessive, and clutter memory. So we're not going to do this.