Update design to fix non-protected broadcast from system issue

ActivityManager checks if there is any non-protected broadcast
sent from the system to prevent malwares sending the fake intent.
This could be fixed with declaring it as a protected broadcast
which is the current implementation. However, the uid in the
AndroidManifest for tethering is networkstack uid. Though system
only check whether the intent is defined as protected broadcast
or not regardless of where the protected intent is defined, it
is confusing to define the protected intent in tethering
AndroidManifest. Thus, update to alternative way to fulfill
the protection in ActivityManager to declare the required
permission in the broadcast filter and specify the expected
package name of the intent.

Bug: 269383522
Bug: 259000745
Test: atest FrameworksNetTests
Test: manually check no am_wtf log complains sending non-protected
      broadcast from system
Change-Id: I04986aed4fb92f85adcbac8a61665f3f465e2eab