refactor(magnification): seperate compute bounds and draw border related logics

Move the recomputeBounds() out of draw borders logics

Bug: 333647467
Test: atest AccessibilityMagnificationTest
      atest FullscreenMagnificationControllerTest
Flag: ACONFIG always_draw_magnification_fullscreen_border DEVELOPMENT
Change-Id: I8d9299d2bc22c480cc82f22e3755ce06977aa9e4
3 files changed