Allow the shell user to run tzdatacheck

Allow the shell user to run tzdatacheck, which is required
to enable a new host side test.

This change also adds some additional checks to
tzdatacheck.te to ensure that OEMs opening up permissions
further don't accidentally create a security hole.

Bug: 31008728
Test: Ran CTS
Change-Id: I6ebfb467526b6b2ea08f891420eea24c81ed1e36