Apply check to Activity starting flow if it is a SandboxedActivity

SandboxedActivity is a new an Activity which is part of the SdkSanbox
App and will run insdie sandbox process.
This cl adds a check to starting activity flow in case that the activity
is SandboxedActivity to ensure that the caller app can start it.

Test: atest com.android.server.sdksandbox.SdkSandboxManagerServiceUnitTest
Bug: 261730613
Change-Id: Ia862bfd8a2108d36ae7f08ed657f4b797cde6076