Only bind footer  when flag is enabled.

The binding of the footer, empty shade and accessibility importance
should be protected by the footer refactor flag.

Bug: 293167744
Fix: 312914620
Test: checked manually that things work with the flag on/off
Flag: ACONFIG com.android.systemui.notifications_footer_view_refactor DEVELOPMENT

Change-Id: I5b0380dac56b9845083ec6dfbc06d41652c8a19d
1 file changed