DO NOT MERGE: De-guava BroadcastInterceptingContext and move it to testutils.

DO NOT MERGE: De-guava BroadcastInterceptingContext and move it to testutils.

Removing the static dependency on guava reduces test compile time
by about 20 seconds on a Z840, thus substantially speeding up the
compile/test cycle.

Make FutureIntent public instead of package-private because it is
used directly by NetworkPolicyManagementServiceTest, which as of
this CL is now in a different package.

(cherry picked from commit 281a17c9580de5c9898be7d9654d428801976511)

Test: runtest frameworks-services -c com.android.server.ConnectivityServiceTest  # PASS
Test: runtest frameworks-services -c com.android.server.NetworkPolicyManagerServiceTest  # PASS
Test: runtest frameworks-services -c com.android.server.net.NetworkStatsServiceTest  # PASS
Test: runtest frameworks-services -c com.android.server.NetworkManagementServiceTest  # Already failing.
Bug: 31479480

(cherry picked from commit 3c295b59f5767904656235db48692906148ab631)

Change-Id: I8a95d4618dced81f173d2b38b9c1dfe3860b348a