Move Privacy dots to new DecorProvider

Provide privacy dot information as DecorProvider, and we can reduce the
dependency to privacy dot, and let ScreenDecorations focus on
interactions between DecorProvider and related views life cycle.

Bug: 213291394
Test: atest ScreenDecorationsTest
            PrivacyDotDecorProviderFactoryTest
            OverlayWindowTest

Change-Id: I2ecab3f145fbb5c72114455054763b5db614a003