Adding API for providing AppMarket intent to Launcher.

Launchers can use this API to start the App Market intent
for a profile, which they are otherwise not allowed.

The API is only accessible to system launcher ATM as it
can enlist activities in private space.
At a later point (b/303803157) this would be fine tuned.

Bug: 308064949
Test: atest LauncherAppsTest
Change-Id: I4c749a3aa1d1d28de10c23df554fa8c2d6027723