Block private space creation based on device conditions

This change adds logic to disable private space creation when
the below mentioned device conditions are met:

- Device has low RAM (based on ActivityManager.isLowRamDevice)
- Device is a TV, Automotive devices, or a Watch
- The parent user has retriciton DISALLOW_ADD_PRIVATE_PROFILE
- The parent user is non-system user

The change also adds a hidden API (canAddPrivateProfile) that
checks for all the above mentioned conditions. This API can be used
by callers to check if the private space creation is supported
on the device and parent user.

Test: atest UserManagerServiceTest
atest UserManagerTest
Bug: 290333800

Change-Id: Iea123c2e4646980eca6253b2f063799d92320b1a