Fade component integration into Dialog

[pixel-perfectionist]

Analyze existing Dialog and DialogBackdrop motion implementations for compatibility with Fade motion.
Modify the Dialog and DialogBackdrop components to include Fade motion using reusable motion atoms.

UPD: 11/18 Integration of the Fade component is closely linked with ongoing RFC reviews. The foundational work, including reusable motion atoms and updated API proposals, is complete and pending review. Once aligned with RFCs, the Fade component integration can proceed with minimal adjustments, as most of the code is already prepared in branches.

#33259
#33288

• Fade motion is seamlessly integrated into both Dialog and DialogBackdrop components.
• All animations perform as expected across supported browsers and devices.
• Motion complies with Fluent UI guidelines, ensuring accessibility and design consistency.
• Unit tests and integration tests validate the functionality of Fade motion within Dialog and DialogBackdrop.
• Cross-browser testing is completed and any inconsistencies resolved.