[bc25] Allow dual quick settings shade to align to the bottom.

This allows QuickSettingsShadeScene to be customized such that instead
of align to the top, it is now align to the bottom (positioning to the
horizontal side remains unchanged).

This also adds a new transition to the framework so that when it is on
the bottom, the scene appears from the bottom edge rather than the top.

Flag: com.android.systemui.dual_shade
Bug: 343744476
Test: Manual; Change config.xml content to be true instead, and then
call on adb shell service call statusbar 1 to see animation.
Test: Manual; verify on device with flexiglass flag off still works.

Change-Id: I2cf2dacf6902220e9b8ba9e9fdf49fd85f4d0e10