Add a one-off shell command to disable verification

The package verification is provided by Play whose behavior
is not controlled by framework. For CTS, such verification
is unnecessary because we have dedicated GTS for that. We add
a shell command to disable verification when installing packages
in CTS to avoid unexpected behavior caused by external entities
to improve stableness of tests.

There is no reduction in safety:
1. This feature is only available to apps with shell
   permissions. Such apps can already skip verification
   by changing a settings value.
2. The command works in a one-off manner. This command
   will only allow the next created session to bypass verification.
   This command requires a uid which prevents accidentally granting
   the ability to other apps.

Bug: 264963480
Test: atest CtsStagedInstallHostTestCases
Change-Id: I26e60837139007e98e99f44aeb0eb13716d91523