Laravel code quality improvements.

[simjanos-dev]

This is a long list of tasks to improve the code quality. I will probably implement them throughout multiple updates.

Tasks:

• Replace the TextBlock model with a TextBlock service
• Move Goal related logic to a new GoalService class (look inside word and phrase model setStage functions)
• Rename lessons to chapters Rename lessons to chapters in the code #20

Rename media player:

• Rename MediaPLayerController to JellyfinController

Moving business logic from controllers to service classes and DB logic into models,
replacing return values with proper HTTP responses,
and creating request classes and writing proper validations:

• AnkiController
• BookController
• ChapterController
• DictionaryController
• GoalController
• HomeController
• ImageController
• ImportController
• MediaPlayerController
• ReviewController
• SettingsController
• UserController
• VocabularyController

[simjanos-dev]

Finally finished. 🎉🎉🎉