Make PrivateSpaceSettingsButton instead of having just the imageView.

This way we can keep the click listener in this PrivateSpaceSettingsButton.java class.
- Moved itemInfo creation to PrivateSpaceSettingsButton and created a test class

bug: 341053089
Test: manually - presubmit video: https://drive.google.com/file/d/1_TCGrILvwmMpxbgIcbOcpB2AxeBJbyNf/view?usp=sharing
Flag: Aconfig com.android.launcher3.enable_private_space Nextfood
Change-Id: I79cd319274f4445dd00bc257be81728360d09684