refactor(magnification): Rename methods setScale based on its targets

We would like to rename the methods setScale() as setScaleForWindowMagnification() to provide more precise method names.

Bug: 310109308
Test: manually. Renaming methods
      atest MagnificationTest
      atest MagnificationConnectionManagerTest
      atest MagnificationControllerTest
      atest WindowMagnificationControllerTest
      atest MagnificationConnectionWrapperTest
Flag: NA
Change-Id: I0fca90e2f3e99685dc90ea5df03414fb72c6c4a0