refactor(magnification): Renaming WindowMagnificationManager class as...

refactor(magnification): Renaming WindowMagnificationManager class as MagnificationConnectionManager

The class WindowMagnificationManager handles stuffs more than magnification window mode. Therefore, we would like to rename the class to improve the readability of our codebase and avoid confusion. Since the class targets at managing the magnification connection operations, we will name it MagnificationConnectionManager.

Bug: 310109308
Test: manually. Renaming the class
      atest MagnificationProcessorTest
      atest MagnificationControllerTest
      atest MagnificationConnectionManagerTest
      atest WindowMagnificationGestureHandlerTest
      atest AccessibilityManagerServiceTest
Flag: NA
Change-Id: Ie4d53ba63aa6d6cadf4cf455f1ece534a54cad0a