This commit prepares the documentation directories for future tutorials organized by directory.
Also, it moves the Angular Libraries topic from the Tutorials section to Developer Guides in TOC
PR Close#48162
Refactored the DI section to improve doc quality, reduce cognitive load and drive consistency.
- Added an overview with prerequisites and doc cards that point to rest of the DI content
- Added introduction topic with topic purpose, value proposition and "fail fast"
- Broke apart complex concepts into simpler tasks
- Unified tone and language for each topic
- Added new content based on SME feedback
- Deleted obsolete content
PR Close#44466