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

refactor(magnification): Renaming WindowMagnificationConnectionImpl class as MagnificationConnectionImpl

The connection 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.

Bug: 310109308
Test: manually. Renaming the class
      atest MagnificationTest
      atest MagnificationSettingsControllerTest
      atest WindowMagnificationSettingsTest
      atest WindowMagnificationControllerTest
      atest MagnificationconnectionManagerTest
      atest MagnificationControllerTest
Flag: NA
Change-Id: I1360adabf6c2d80c69d2390b6b842c01391d6139