refactor(magnification): Renaming WindowMagnificationConnectionWrapper class...

refactor(magnification): Renaming WindowMagnificationConnectionWrapper class as MagnificationConnectionWrapper

The class handles not only the window mode, but also the fullscreen
fullscreen mode. Therefore, we would like to remove "window" from the
name to avoid the confusion.

Bug: 310109308
Test: manually
      atest MagnificationConnectionWrapperTest
      atest WindowMagnificationManagerTest
Flag: NA
Change-Id: Id09c8609041f34a18934ffaad758982250e1ca77