fix(magnify_ime): magnifies navBar when mouse or keyboard connected

Magnifying the nav bar is disabled in the previous commit [1].
This change adds back the magnification behavior of TYPE_NAVIGATION_BAR
but only when there's an active mouse or keyboard.

When a mouse or a keyboard is connected, we can expect that the user is
primarily using these devices to interact, instead of touch, thus,
- We don't need to keep showing 3 button bar at the same position of the
  screen.
- Instread, we want to magnify the entire screen to make sure all content
  user interacts, especially a task bar in large screen, are magnified.

[1] Icd42a530315717473cf93706aee625993821122e

Bug: 418892460
Test: WindowStateTests
Test: manually, connect / disconnect a mouse and a keyboard, toggle "magnify keyboard"
Flag: com.android.server.accessibility.enable_magnification_magnify_nav_bar_and_ime

Change-Id: I6db97a1f6e87a03359fcabb658b18932d3e899e1